[PATCH v2 1/2] Replacing CONFIG_VNC_PNG with CONFIG_PNG

[PATCH v2 1/2] Replacing CONFIG_VNC_PNG with CONFIG_PNG

[Kshitij Suri]

Libpng is only detected if VNC is enabled currently. This patch adds a
generalised png option in the meson build which is aimed to replace use of
CONFIG_VNC_PNG with CONFIG_PNG.

Signed-off-by: Kshitij Suri <kshitij.suri@nutanix.com>
---
 meson.build        |  9 ++++-----
 meson_options.txt  |  4 ++--
 ui/vnc-enc-tight.c | 18 +++++++++---------
 ui/vnc.c           |  4 ++--
 ui/vnc.h           |  2 +-
 5 files changed, 18 insertions(+), 19 deletions(-)

diff --git a/meson.build b/meson.build
index 8df40bfac4..3b67f83a2c 100644
--- a/meson.build
+++ b/meson.build
@@ -1112,14 +1112,13 @@ if gtkx11.found()
   x11 = dependency('x11', method: 'pkg-config', required: gtkx11.found(),
                    kwargs: static_kwargs)
 endif
+png = dependency('libpng', required: get_option('png'),
+                 method: 'pkg-config', kwargs: static_kwargs)
 vnc = not_found
-png = not_found
 jpeg = not_found
 sasl = not_found
 if get_option('vnc').allowed() and have_system
   vnc = declare_dependency() # dummy dependency
-  png = dependency('libpng', required: get_option('vnc_png'),
-                   method: 'pkg-config', kwargs: static_kwargs)
   jpeg = dependency('libjpeg', required: get_option('vnc_jpeg'),
                     method: 'pkg-config', kwargs: static_kwargs)
   sasl = cc.find_library('sasl2', has_headers: ['sasl/sasl.h'],
@@ -1537,9 +1536,9 @@ config_host_data.set('CONFIG_TPM', have_tpm)
 config_host_data.set('CONFIG_USB_LIBUSB', libusb.found())
 config_host_data.set('CONFIG_VDE', vde.found())
 config_host_data.set('CONFIG_VHOST_USER_BLK_SERVER', have_vhost_user_blk_server)
+config_host_data.set('CONFIG_PNG', png.found())
 config_host_data.set('CONFIG_VNC', vnc.found())
 config_host_data.set('CONFIG_VNC_JPEG', jpeg.found())
-config_host_data.set('CONFIG_VNC_PNG', png.found())
 config_host_data.set('CONFIG_VNC_SASL', sasl.found())
 config_host_data.set('CONFIG_VIRTFS', have_virtfs)
 config_host_data.set('CONFIG_VTE', vte.found())
@@ -3579,11 +3578,11 @@ summary_info += {'curses support':    curses}
 summary_info += {'virgl support':     virgl}
 summary_info += {'curl support':      curl}
 summary_info += {'Multipath support': mpathpersist}
+summary_info += {'PNG support':       png}
 summary_info += {'VNC support':       vnc}
 if vnc.found()
   summary_info += {'VNC SASL support':  sasl}
   summary_info += {'VNC JPEG support':  jpeg}
-  summary_info += {'VNC PNG support':   png}
 endif
 if targetos not in ['darwin', 'haiku', 'windows']
   summary_info += {'OSS support':     oss}
diff --git a/meson_options.txt b/meson_options.txt
index 52b11cead4..d85734f8e6 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -177,12 +177,12 @@ option('vde', type : 'feature', value : 'auto',
        description: 'vde network backend support')
 option('virglrenderer', type : 'feature', value : 'auto',
        description: 'virgl rendering support')
+option('png', type : 'feature', value : 'auto',
+       description: 'PNG support with libpng')
 option('vnc', type : 'feature', value : 'auto',
        description: 'VNC server')
 option('vnc_jpeg', type : 'feature', value : 'auto',
        description: 'JPEG lossy compression for VNC server')
-option('vnc_png', type : 'feature', value : 'auto',
-       description: 'PNG compression for VNC server')
 option('vnc_sasl', type : 'feature', value : 'auto',
        description: 'SASL authentication for VNC server')
 option('vte', type : 'feature', value : 'auto',
diff --git a/ui/vnc-enc-tight.c b/ui/vnc-enc-tight.c
index cebd35841a..a23ad712eb 100644
--- a/ui/vnc-enc-tight.c
+++ b/ui/vnc-enc-tight.c
@@ -32,7 +32,7 @@
    INT32 definitions between jmorecfg.h (included by jpeglib.h) and
    Win32 basetsd.h (included by windows.h). */
 
-#ifdef CONFIG_VNC_PNG
+#ifdef CONFIG_PNG
 /* The following define is needed by pngconf.h. Otherwise it won't compile,
    because setjmp.h was already included by qemu-common.h. */
 #define PNG_SKIP_SETJMP_CHECK
@@ -95,7 +95,7 @@ static const struct {
 };
 #endif
 
-#ifdef CONFIG_VNC_PNG
+#ifdef CONFIG_PNG
 static const struct {
     int png_zlib_level, png_filters;
 } tight_png_conf[] = {
@@ -919,7 +919,7 @@ static int send_full_color_rect(VncState *vs, int x, int y, int w, int h)
     int stream = 0;
     ssize_t bytes;
 
-#ifdef CONFIG_VNC_PNG
+#ifdef CONFIG_PNG
     if (tight_can_send_png_rect(vs, w, h)) {
         return send_png_rect(vs, x, y, w, h, NULL);
     }
@@ -966,7 +966,7 @@ static int send_mono_rect(VncState *vs, int x, int y,
     int stream = 1;
     int level = tight_conf[vs->tight->compression].mono_zlib_level;
 
-#ifdef CONFIG_VNC_PNG
+#ifdef CONFIG_PNG
     if (tight_can_send_png_rect(vs, w, h)) {
         int ret;
         int bpp = vs->client_pf.bytes_per_pixel * 8;
@@ -1020,7 +1020,7 @@ static int send_mono_rect(VncState *vs, int x, int y,
 struct palette_cb_priv {
     VncState *vs;
     uint8_t *header;
-#ifdef CONFIG_VNC_PNG
+#ifdef CONFIG_PNG
     png_colorp png_palette;
 #endif
 };
@@ -1082,7 +1082,7 @@ static int send_palette_rect(VncState *vs, int x, int y,
     int colors;
     ssize_t bytes;
 
-#ifdef CONFIG_VNC_PNG
+#ifdef CONFIG_PNG
     if (tight_can_send_png_rect(vs, w, h)) {
         return send_png_rect(vs, x, y, w, h, palette);
     }
@@ -1233,7 +1233,7 @@ static int send_jpeg_rect(VncState *vs, int x, int y, int w, int h, int quality)
 /*
  * PNG compression stuff.
  */
-#ifdef CONFIG_VNC_PNG
+#ifdef CONFIG_PNG
 static void write_png_palette(int idx, uint32_t pix, void *opaque)
 {
     struct palette_cb_priv *priv = opaque;
@@ -1379,7 +1379,7 @@ static int send_png_rect(VncState *vs, int x, int y, int w, int h,
     buffer_reset(&vs->tight->png);
     return 1;
 }
-#endif /* CONFIG_VNC_PNG */
+#endif /* CONFIG_PNG */
 
 static void vnc_tight_start(VncState *vs)
 {
@@ -1706,7 +1706,7 @@ void vnc_tight_clear(VncState *vs)
 #ifdef CONFIG_VNC_JPEG
     buffer_free(&vs->tight->jpeg);
 #endif
-#ifdef CONFIG_VNC_PNG
+#ifdef CONFIG_PNG
     buffer_free(&vs->tight->png);
 #endif
 }
diff --git a/ui/vnc.c b/ui/vnc.c
index 3ccd33dedc..a588ddff1c 100644
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -2165,7 +2165,7 @@ static void set_encodings(VncState *vs, int32_t *encodings, size_t n_encodings)
             vs->features |= VNC_FEATURE_TIGHT_MASK;
             vs->vnc_encoding = enc;
             break;
-#ifdef CONFIG_VNC_PNG
+#ifdef CONFIG_PNG
         case VNC_ENCODING_TIGHT_PNG:
             vs->features |= VNC_FEATURE_TIGHT_PNG_MASK;
             vs->vnc_encoding = enc;
@@ -3248,7 +3248,7 @@ static void vnc_connect(VncDisplay *vd, QIOChannelSocket *sioc,
 #ifdef CONFIG_VNC_JPEG
     buffer_init(&vs->tight->jpeg,     "vnc-tight-jpeg/%p", sioc);
 #endif
-#ifdef CONFIG_VNC_PNG
+#ifdef CONFIG_PNG
     buffer_init(&vs->tight->png,      "vnc-tight-png/%p", sioc);
 #endif
     buffer_init(&vs->zlib.zlib,      "vnc-zlib/%p", sioc);
diff --git a/ui/vnc.h b/ui/vnc.h
index a7149831f9..a60fb13115 100644
--- a/ui/vnc.h
+++ b/ui/vnc.h
@@ -201,7 +201,7 @@ typedef struct VncTight {
 #ifdef CONFIG_VNC_JPEG
     Buffer jpeg;
 #endif
-#ifdef CONFIG_VNC_PNG
+#ifdef CONFIG_PNG
     Buffer png;
 #endif
     int levels[4];
-- 
2.22.3

[PATCH v2 2/2] Added parameter to take screenshot with screendump as

[Kshitij Suri]

From: "kshitij.suri" <kshitij.suri@nutanix.com>

Currently screendump only supports PPM format, which is un-compressed and not
standard. Added a "format" parameter to qemu monitor screendump capabilites
to support PNG image capture using libpng. The param was added in QAPI schema
of screendump present in ui.json along with png_save() function which converts
pixman_image to PNG. HMP command equivalent was also modified to support the
feature.

Example usage:
{ "execute": "screendump", "arguments": { "filename": "/tmp/image",
"format":"png" } }

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/718

Signed-off-by: Kshitij Suri <kshitij.suri@nutanix.com>
---
diff to v1:
  - Removed repeated alpha conversion operation.
  - Modified logic to mirror png conversion in vnc-enc-tight.c file.
  - Added a new CONFIG_PNG parameter for libpng support.
  - Changed input format to enum instead of string.
  - Improved error handling.
 hmp-commands.hx    |  11 ++---
 monitor/hmp-cmds.c |  19 ++++++++-
 qapi/ui.json       |  24 +++++++++--
 ui/console.c       | 102 +++++++++++++++++++++++++++++++++++++++++++--
 4 files changed, 144 insertions(+), 12 deletions(-)

diff --git a/hmp-commands.hx b/hmp-commands.hx
index 70a9136ac2..5eda4eeb24 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -244,17 +244,18 @@ ERST
 
     {
         .name       = "screendump",
-        .args_type  = "filename:F,device:s?,head:i?",
-        .params     = "filename [device [head]]",
-        .help       = "save screen from head 'head' of display device 'device' "
-                      "into PPM image 'filename'",
+        .args_type  = "filename:F,device:s?,head:i?,format:f?",
+        .params     = "filename [device [head]] [format]",
+        .help       = "save screen from head 'head' of display device 'device'"
+                      "in specified format 'format' as image 'filename'."
+                      "Currently only 'png' and 'ppm' formats are supported.",
         .cmd        = hmp_screendump,
         .coroutine  = true,
     },
 
 SRST
 ``screendump`` *filename*
-  Save screen into PPM image *filename*.
+  Save screen as an image *filename*, with default format of PPM.
 ERST
 
     {
diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
index 8c384dc1b2..9a640146eb 100644
--- a/monitor/hmp-cmds.c
+++ b/monitor/hmp-cmds.c
@@ -1677,9 +1677,26 @@ hmp_screendump(Monitor *mon, const QDict *qdict)
     const char *filename = qdict_get_str(qdict, "filename");
     const char *id = qdict_get_try_str(qdict, "device");
     int64_t head = qdict_get_try_int(qdict, "head", 0);
+    const char *input_format  = qdict_get_str(qdict, "format");
     Error *err = NULL;
+    ImageFormat format;
 
-    qmp_screendump(filename, id != NULL, id, id != NULL, head, &err);
+    int val = qapi_enum_parse(&ImageFormat_lookup, input_format, -1, &err);
+    if (val < 0) {
+        goto end;
+    }
+
+    switch (val) {
+    case IMAGE_FORMAT_PNG:
+        format = IMAGE_FORMAT_PNG;
+        break;
+    default:
+        format = IMAGE_FORMAT_PPM;
+    }
+
+    qmp_screendump(filename, id != NULL, id, id != NULL, head,
+                   input_format != NULL, format, &err);
+end:
     hmp_handle_error(mon, err);
 }
 
diff --git a/qapi/ui.json b/qapi/ui.json
index 9354f4c467..a6d994ba2c 100644
--- a/qapi/ui.json
+++ b/qapi/ui.json
@@ -73,12 +73,27 @@
 ##
 { 'command': 'expire_password', 'data': {'protocol': 'str', 'time': 'str'} }
 
+##
+# @ImageFormat:
+#
+# Supported image format types.
+#
+# @png: PNG format
+#
+# @ppm: PPM format
+#
+# Since: 7.0
+#
+##
+{ 'enum': 'ImageFormat',
+  'data': ['ppm', 'png'] }
+
 ##
 # @screendump:
 #
-# Write a PPM of the VGA screen to a file.
+# Write a screenshot of the VGA screen to a file.
 #
-# @filename: the path of a new PPM file to store the image
+# @filename: the path of a new file to store the image
 #
 # @device: ID of the display device that should be dumped. If this parameter
 #          is missing, the primary display will be used. (Since 2.12)
@@ -87,6 +102,8 @@
 #        parameter is missing, head #0 will be used. Also note that the head
 #        can only be specified in conjunction with the device ID. (Since 2.12)
 #
+# @format: image format for screendump is specified. (default: ppm) (Since 7.0)
+#
 # Returns: Nothing on success
 #
 # Since: 0.14
@@ -99,7 +116,8 @@
 #
 ##
 { 'command': 'screendump',
-  'data': {'filename': 'str', '*device': 'str', '*head': 'int'},
+  'data': {'filename': 'str', '*device': 'str', '*head': 'int',
+           '*format': 'ImageFormat'},
   'coroutine': true }
 
 ##
diff --git a/ui/console.c b/ui/console.c
index 40eebb6d2c..aab561e1ac 100644
--- a/ui/console.c
+++ b/ui/console.c
@@ -37,6 +37,9 @@
 #include "exec/memory.h"
 #include "io/channel-file.h"
 #include "qom/object.h"
+#ifdef CONFIG_PNG
+#include <png.h>
+#endif
 
 #define DEFAULT_BACKSCROLL 512
 #define CONSOLE_CURSOR_PERIOD 500
@@ -289,6 +292,89 @@ void graphic_hw_invalidate(QemuConsole *con)
     }
 }
 
+#ifdef CONFIG_PNG
+/**
+ * png_save: Take a screenshot as PNG
+ *
+ * Saves screendump as a PNG file
+ *
+ * Returns true for success or false for error.
+ *
+ * @fd: File descriptor for PNG file.
+ * @image: Image data in pixman format.
+ * @errp: Pointer to an error.
+ */
+static bool png_save(int fd, pixman_image_t *image, Error **errp)
+{
+    int width = pixman_image_get_width(image);
+    int height = pixman_image_get_height(image);
+    g_autofree png_struct *png_ptr = NULL;
+    g_autofree png_info *info_ptr = NULL;
+    g_autoptr(pixman_image_t) linebuf =
+                            qemu_pixman_linebuf_create(PIXMAN_a8r8g8b8, width);
+    uint8_t *buf = (uint8_t *)pixman_image_get_data(linebuf);
+    FILE *f = fdopen(fd, "wb");
+    int y;
+    if (!f) {
+        error_setg_errno(errp, errno,
+                         "Failed to create file from file descriptor");
+        return false;
+    }
+
+    png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL,
+                                      NULL, NULL);
+    if (!png_ptr) {
+        error_setg(errp, "PNG creation failed. Unable to write struct");
+        fclose(f);
+        return false;
+    }
+
+    info_ptr = png_create_info_struct(png_ptr);
+
+    if (!info_ptr) {
+        error_setg(errp, "PNG creation failed. Unable to write info");
+        fclose(f);
+        png_destroy_write_struct(&png_ptr, &info_ptr);
+        return false;
+    }
+
+    png_init_io(png_ptr, f);
+
+    png_set_IHDR(png_ptr, info_ptr, width, height, 8,
+                 PNG_COLOR_TYPE_RGB_ALPHA, PNG_INTERLACE_NONE,
+                 PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+
+    png_write_info(png_ptr, info_ptr);
+
+    for (y = 0; y < height; ++y) {
+        qemu_pixman_linebuf_fill(linebuf, image, width, 0, y);
+        png_write_row(png_ptr, buf);
+    }
+    qemu_pixman_image_unref(linebuf);
+
+    png_write_end(png_ptr, NULL);
+
+    png_destroy_write_struct(&png_ptr, &info_ptr);
+
+    if (fclose(f) != 0) {
+        error_setg_errno(errp, errno,
+                         "PNG creation failed. Unable to close file");
+        return false;
+    }
+
+    return true;
+}
+
+#else /* no png support */
+
+static bool png_save(int fd, pixman_image_t *image, Error **errp)
+{
+    error_setg(errp, "Enable PNG support with libpng for screendump");
+    return false;
+}
+
+#endif /* CONFIG_PNG */
+
 static bool ppm_save(int fd, pixman_image_t *image, Error **errp)
 {
     int width = pixman_image_get_width(image);
@@ -327,7 +413,8 @@ static void graphic_hw_update_bh(void *con)
 /* Safety: coroutine-only, concurrent-coroutine safe, main thread only */
 void coroutine_fn
 qmp_screendump(const char *filename, bool has_device, const char *device,
-               bool has_head, int64_t head, Error **errp)
+               bool has_head, int64_t head, bool has_format,
+               ImageFormat format, Error **errp)
 {
     g_autoptr(pixman_image_t) image = NULL;
     QemuConsole *con;
@@ -383,8 +470,17 @@ qmp_screendump(const char *filename, bool has_device, const char *device,
      * yields and releases the BQL. It could produce corrupted dump, but
      * it should be otherwise safe.
      */
-    if (!ppm_save(fd, image, errp)) {
-        qemu_unlink(filename);
+
+    if (has_format && format == IMAGE_FORMAT_PNG) {
+        /* PNG format specified for screendump */
+        if (!png_save(fd, image, errp)) {
+            qemu_unlink(filename);
+        }
+    } else {
+        /* PPM format specified/default for screendump */
+        if (!ppm_save(fd, image, errp)) {
+            qemu_unlink(filename);
+        }
     }
 }
 
-- 
2.22.3

Re: [PATCH v2 1/2] Replacing CONFIG_VNC_PNG with CONFIG_PNG

[Paolo Bonzini]

On 3/15/22 05:47, Kshitij Suri wrote:
> +png = dependency('libpng', required: get_option('png'),
> +                 method: 'pkg-config', kwargs: static_kwargs)

The full way to write it would be:

png = not_found
if get_option('png').allowed() and have_system
   png = dependency('libpng', required: get_option('png'),
                    method: 'pkg-config', kwargs: static_kwargs)
endif

but we can now also use

png = dependency('libpng',
                  required: get_option('png').disable_auto_if(not have_system),
                  method: 'pkg-config', kwargs: static_kwargs)

Use the one that you prefer.

Paolo

Re: [PATCH v2 2/2] Added parameter to take screenshot with screendump as

[Markus Armbruster]

Kshitij Suri <kshitij.suri@nutanix.com> writes:

> From: "kshitij.suri" <kshitij.suri@nutanix.com>
>
> Currently screendump only supports PPM format, which is un-compressed and not
> standard. Added a "format" parameter to qemu monitor screendump capabilites
> to support PNG image capture using libpng. The param was added in QAPI schema
> of screendump present in ui.json along with png_save() function which converts
> pixman_image to PNG. HMP command equivalent was also modified to support the
> feature.
>
> Example usage:
> { "execute": "screendump", "arguments": { "filename": "/tmp/image",
> "format":"png" } }
>
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/718
>
> Signed-off-by: Kshitij Suri <kshitij.suri@nutanix.com>
> ---
> diff to v1:
>   - Removed repeated alpha conversion operation.
>   - Modified logic to mirror png conversion in vnc-enc-tight.c file.
>   - Added a new CONFIG_PNG parameter for libpng support.
>   - Changed input format to enum instead of string.
>   - Improved error handling.
>  hmp-commands.hx    |  11 ++---
>  monitor/hmp-cmds.c |  19 ++++++++-
>  qapi/ui.json       |  24 +++++++++--
>  ui/console.c       | 102 +++++++++++++++++++++++++++++++++++++++++++--
>  4 files changed, 144 insertions(+), 12 deletions(-)
>
> diff --git a/hmp-commands.hx b/hmp-commands.hx
> index 70a9136ac2..5eda4eeb24 100644
> --- a/hmp-commands.hx
> +++ b/hmp-commands.hx
> @@ -244,17 +244,18 @@ ERST
>  
>      {
>          .name       = "screendump",
> -        .args_type  = "filename:F,device:s?,head:i?",
> -        .params     = "filename [device [head]]",
> -        .help       = "save screen from head 'head' of display device 'device' "
> -                      "into PPM image 'filename'",
> +        .args_type  = "filename:F,device:s?,head:i?,format:f?",
> +        .params     = "filename [device [head]] [format]",
> +        .help       = "save screen from head 'head' of display device 'device'"
> +                      "in specified format 'format' as image 'filename'."
> +                      "Currently only 'png' and 'ppm' formats are supported.",
>          .cmd        = hmp_screendump,
>          .coroutine  = true,
>      },
>  
>  SRST
>  ``screendump`` *filename*
> -  Save screen into PPM image *filename*.
> +  Save screen as an image *filename*, with default format of PPM.
>  ERST
>  
>      {
> diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
> index 8c384dc1b2..9a640146eb 100644
> --- a/monitor/hmp-cmds.c
> +++ b/monitor/hmp-cmds.c
> @@ -1677,9 +1677,26 @@ hmp_screendump(Monitor *mon, const QDict *qdict)
>      const char *filename = qdict_get_str(qdict, "filename");
>      const char *id = qdict_get_try_str(qdict, "device");
>      int64_t head = qdict_get_try_int(qdict, "head", 0);
> +    const char *input_format  = qdict_get_str(qdict, "format");
>      Error *err = NULL;
> +    ImageFormat format;
>  
> -    qmp_screendump(filename, id != NULL, id, id != NULL, head, &err);

The second id != NULL looks wrong.  Shouldn't it be head != NULL?
Not your patch's fault, of course.

> +    int val = qapi_enum_parse(&ImageFormat_lookup, input_format, -1, &err);
> +    if (val < 0) {
> +        goto end;
> +    }
> +
> +    switch (val) {
> +    case IMAGE_FORMAT_PNG:
> +        format = IMAGE_FORMAT_PNG;
> +        break;
> +    default:
> +        format = IMAGE_FORMAT_PPM;
> +    }
> +
> +    qmp_screendump(filename, id != NULL, id, id != NULL, head,
> +                   input_format != NULL, format, &err);
> +end:
>      hmp_handle_error(mon, err);
>  }

This isn't quite right.

qapi_enum_parse() is awkward to use.

If its second argument @input_format is null, it returns its third
argument -1.

Else, it @input_format is a valid enum string, it returns the
enumeration value, i.e. either IMAGE_FORMAT_PPM or IMAGE_FORMAT_PNG.

Else, it sets an error and returns its third argument -1.

If @input_format is null, I suspect your code jumps to
hmp_handle_error() with a null @err.  Silently does nothing.

It should default to IMAGE_FORMAT_PPM instead.

I think you want something like this (completely untested):

    val = qapi_enum_parse(&ImageFormat_lookup, input_format,
                          IMAGE_FORMAT_PPM, &err);
    if (err) {
        goto end;
    }

    qmp_screendump(filename, id != NULL, id, head != NULL, head,
                   input_format != NULL, val, &err);

>  
> diff --git a/qapi/ui.json b/qapi/ui.json
> index 9354f4c467..a6d994ba2c 100644
> --- a/qapi/ui.json
> +++ b/qapi/ui.json
> @@ -73,12 +73,27 @@
>  ##
>  { 'command': 'expire_password', 'data': {'protocol': 'str', 'time': 'str'} }
>  
> +##
> +# @ImageFormat:
> +#
> +# Supported image format types.
> +#
> +# @png: PNG format
> +#
> +# @ppm: PPM format
> +#
> +# Since: 7.0
> +#
> +##
> +{ 'enum': 'ImageFormat',
> +  'data': ['ppm', 'png'] }
> +
>  ##
>  # @screendump:
>  #
> -# Write a PPM of the VGA screen to a file.
> +# Write a screenshot of the VGA screen to a file.

Let's improve this to

   # Capture the contents of a screen and write it to a file.

>  #
> -# @filename: the path of a new PPM file to store the image
> +# @filename: the path of a new file to store the image
>  #
>  # @device: ID of the display device that should be dumped. If this parameter
>  #          is missing, the primary display will be used. (Since 2.12)
> @@ -87,6 +102,8 @@
>  #        parameter is missing, head #0 will be used. Also note that the head
>  #        can only be specified in conjunction with the device ID. (Since 2.12)
>  #
> +# @format: image format for screendump is specified. (default: ppm) (Since 7.0)
> +#
>  # Returns: Nothing on success
>  #
>  # Since: 0.14
> @@ -99,7 +116,8 @@
>  #
>  ##
>  { 'command': 'screendump',
> -  'data': {'filename': 'str', '*device': 'str', '*head': 'int'},
> +  'data': {'filename': 'str', '*device': 'str', '*head': 'int',
> +           '*format': 'ImageFormat'},
>    'coroutine': true }
>  
>  ##

[...]

> @@ -327,7 +413,8 @@ static void graphic_hw_update_bh(void *con)
>  /* Safety: coroutine-only, concurrent-coroutine safe, main thread only */
>  void coroutine_fn
>  qmp_screendump(const char *filename, bool has_device, const char *device,
> -               bool has_head, int64_t head, Error **errp)
> +               bool has_head, int64_t head, bool has_format,
> +               ImageFormat format, Error **errp)

Please break the line like

                  bool has_head, int64_t head,
                  bool has_format, ImageFormat format, Error **errp)

>  {
>      g_autoptr(pixman_image_t) image = NULL;
>      QemuConsole *con;
> @@ -383,8 +470,17 @@ qmp_screendump(const char *filename, bool has_device, const char *device,
>       * yields and releases the BQL. It could produce corrupted dump, but
>       * it should be otherwise safe.
>       */
> -    if (!ppm_save(fd, image, errp)) {
> -        qemu_unlink(filename);
> +
> +    if (has_format && format == IMAGE_FORMAT_PNG) {
> +        /* PNG format specified for screendump */
> +        if (!png_save(fd, image, errp)) {
> +            qemu_unlink(filename);
> +        }
> +    } else {
> +        /* PPM format specified/default for screendump */
> +        if (!ppm_save(fd, image, errp)) {
> +            qemu_unlink(filename);
> +        }
>      }
>  }

Re: [PATCH v2 2/2] Added parameter to take screenshot with screendump as

[Kshitij Suri]

On 16/03/22 6:55 pm, Markus Armbruster wrote:
> Kshitij Suri <kshitij.suri@nutanix.com> writes:
>
>> From: "kshitij.suri" <kshitij.suri@nutanix.com>
>>
>> Currently screendump only supports PPM format, which is un-compressed and not
>> standard. Added a "format" parameter to qemu monitor screendump capabilites
>> to support PNG image capture using libpng. The param was added in QAPI schema
>> of screendump present in ui.json along with png_save() function which converts
>> pixman_image to PNG. HMP command equivalent was also modified to support the
>> feature.
>>
>> Example usage:
>> { "execute": "screendump", "arguments": { "filename": "/tmp/image",
>> "format":"png" } }
>>
>> Resolves: https://urldefense.proofpoint.com/v2/url?u=https-3A__gitlab.com_qemu-2Dproject_qemu_-2D_issues_718&d=DwIBAg&c=s883GpUCOChKOHiocYtGcg&r=utjv19Ej9Fb0TB7_DX0o3faQ-OAm2ypPniPyqVSoj_w&m=UZZDywEeidD1LndEhKddMf_0v-jePIgMYErGImjYyvjYRJFdnv6LAHgRmZ0IpvIL&s=jc09kdvD1ULKCC9RgwWcsK6eweue3ZkyD8F9kCx5yUs&e=
>>
>> Signed-off-by: Kshitij Suri <kshitij.suri@nutanix.com>
>> ---
>> diff to v1:
>>    - Removed repeated alpha conversion operation.
>>    - Modified logic to mirror png conversion in vnc-enc-tight.c file.
>>    - Added a new CONFIG_PNG parameter for libpng support.
>>    - Changed input format to enum instead of string.
>>    - Improved error handling.
>>   hmp-commands.hx    |  11 ++---
>>   monitor/hmp-cmds.c |  19 ++++++++-
>>   qapi/ui.json       |  24 +++++++++--
>>   ui/console.c       | 102 +++++++++++++++++++++++++++++++++++++++++++--
>>   4 files changed, 144 insertions(+), 12 deletions(-)
>>
>> diff --git a/hmp-commands.hx b/hmp-commands.hx
>> index 70a9136ac2..5eda4eeb24 100644
>> --- a/hmp-commands.hx
>> +++ b/hmp-commands.hx
>> @@ -244,17 +244,18 @@ ERST
>>   
>>       {
>>           .name       = "screendump",
>> -        .args_type  = "filename:F,device:s?,head:i?",
>> -        .params     = "filename [device [head]]",
>> -        .help       = "save screen from head 'head' of display device 'device' "
>> -                      "into PPM image 'filename'",
>> +        .args_type  = "filename:F,device:s?,head:i?,format:f?",
>> +        .params     = "filename [device [head]] [format]",
>> +        .help       = "save screen from head 'head' of display device 'device'"
>> +                      "in specified format 'format' as image 'filename'."
>> +                      "Currently only 'png' and 'ppm' formats are supported.",
>>           .cmd        = hmp_screendump,
>>           .coroutine  = true,
>>       },
>>   
>>   SRST
>>   ``screendump`` *filename*
>> -  Save screen into PPM image *filename*.
>> +  Save screen as an image *filename*, with default format of PPM.
>>   ERST
>>   
>>       {
>> diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
>> index 8c384dc1b2..9a640146eb 100644
>> --- a/monitor/hmp-cmds.c
>> +++ b/monitor/hmp-cmds.c
>> @@ -1677,9 +1677,26 @@ hmp_screendump(Monitor *mon, const QDict *qdict)
>>       const char *filename = qdict_get_str(qdict, "filename");
>>       const char *id = qdict_get_try_str(qdict, "device");
>>       int64_t head = qdict_get_try_int(qdict, "head", 0);
>> +    const char *input_format  = qdict_get_str(qdict, "format");
>>       Error *err = NULL;
>> +    ImageFormat format;
>>   
>> -    qmp_screendump(filename, id != NULL, id, id != NULL, head, &err);
> The second id != NULL looks wrong.  Shouldn't it be head != NULL?
> Not your patch's fault, of course.

As per hmp-commands.hx input is of format [device [head]] so maybe

works as a pair. Is it alright if I investigate and send in another patch

after this?

>
>> +    int val = qapi_enum_parse(&ImageFormat_lookup, input_format, -1, &err);
>> +    if (val < 0) {
>> +        goto end;
>> +    }
>> +
>> +    switch (val) {
>> +    case IMAGE_FORMAT_PNG:
>> +        format = IMAGE_FORMAT_PNG;
>> +        break;
>> +    default:
>> +        format = IMAGE_FORMAT_PPM;
>> +    }
>> +
>> +    qmp_screendump(filename, id != NULL, id, id != NULL, head,
>> +                   input_format != NULL, format, &err);
>> +end:
>>       hmp_handle_error(mon, err);
>>   }
> This isn't quite right.
>
> qapi_enum_parse() is awkward to use.
>
> If its second argument @input_format is null, it returns its third
> argument -1.
>
> Else, it @input_format is a valid enum string, it returns the
> enumeration value, i.e. either IMAGE_FORMAT_PPM or IMAGE_FORMAT_PNG.
>
> Else, it sets an error and returns its third argument -1.
>
> If @input_format is null, I suspect your code jumps to
> hmp_handle_error() with a null @err.  Silently does nothing.
>
> It should default to IMAGE_FORMAT_PPM instead.
>
> I think you want something like this (completely untested):
>
>      val = qapi_enum_parse(&ImageFormat_lookup, input_format,
>                            IMAGE_FORMAT_PPM, &err);
>      if (err) {
>          goto end;
>      }
>
>      qmp_screendump(filename, id != NULL, id, head != NULL, head,
>                     input_format != NULL, val, &err);
Oh okay. Will add it in the updated patch.
>
>>   
>> diff --git a/qapi/ui.json b/qapi/ui.json
>> index 9354f4c467..a6d994ba2c 100644
>> --- a/qapi/ui.json
>> +++ b/qapi/ui.json
>> @@ -73,12 +73,27 @@
>>   ##
>>   { 'command': 'expire_password', 'data': {'protocol': 'str', 'time': 'str'} }
>>   
>> +##
>> +# @ImageFormat:
>> +#
>> +# Supported image format types.
>> +#
>> +# @png: PNG format
>> +#
>> +# @ppm: PPM format
>> +#
>> +# Since: 7.0
>> +#
>> +##
>> +{ 'enum': 'ImageFormat',
>> +  'data': ['ppm', 'png'] }
>> +
>>   ##
>>   # @screendump:
>>   #
>> -# Write a PPM of the VGA screen to a file.
>> +# Write a screenshot of the VGA screen to a file.
> Let's improve this to
>
>     # Capture the contents of a screen and write it to a file.
Yes will send it in the updated patch.
>
>>   #
>> -# @filename: the path of a new PPM file to store the image
>> +# @filename: the path of a new file to store the image
>>   #
>>   # @device: ID of the display device that should be dumped. If this parameter
>>   #          is missing, the primary display will be used. (Since 2.12)
>> @@ -87,6 +102,8 @@
>>   #        parameter is missing, head #0 will be used. Also note that the head
>>   #        can only be specified in conjunction with the device ID. (Since 2.12)
>>   #
>> +# @format: image format for screendump is specified. (default: ppm) (Since 7.0)
>> +#
>>   # Returns: Nothing on success
>>   #
>>   # Since: 0.14
>> @@ -99,7 +116,8 @@
>>   #
>>   ##
>>   { 'command': 'screendump',
>> -  'data': {'filename': 'str', '*device': 'str', '*head': 'int'},
>> +  'data': {'filename': 'str', '*device': 'str', '*head': 'int',
>> +           '*format': 'ImageFormat'},
>>     'coroutine': true }
>>   
>>   ##
> [...]
>
>> @@ -327,7 +413,8 @@ static void graphic_hw_update_bh(void *con)
>>   /* Safety: coroutine-only, concurrent-coroutine safe, main thread only */
>>   void coroutine_fn
>>   qmp_screendump(const char *filename, bool has_device, const char *device,
>> -               bool has_head, int64_t head, Error **errp)
>> +               bool has_head, int64_t head, bool has_format,
>> +               ImageFormat format, Error **errp)
> Please break the line like
>
>                    bool has_head, int64_t head,
>                    bool has_format, ImageFormat format, Error **errp)
This does look better. Will update it thank you!
>
>>   {
>>       g_autoptr(pixman_image_t) image = NULL;
>>       QemuConsole *con;
>> @@ -383,8 +470,17 @@ qmp_screendump(const char *filename, bool has_device, const char *device,
>>        * yields and releases the BQL. It could produce corrupted dump, but
>>        * it should be otherwise safe.
>>        */
>> -    if (!ppm_save(fd, image, errp)) {
>> -        qemu_unlink(filename);
>> +
>> +    if (has_format && format == IMAGE_FORMAT_PNG) {
>> +        /* PNG format specified for screendump */
>> +        if (!png_save(fd, image, errp)) {
>> +            qemu_unlink(filename);
>> +        }
>> +    } else {
>> +        /* PPM format specified/default for screendump */
>> +        if (!ppm_save(fd, image, errp)) {
>> +            qemu_unlink(filename);
>> +        }
>>       }
>>   }

Thank you for your review!

Regards,
Kshitij Suri

Re: [PATCH v2 2/2] Added parameter to take screenshot with screendump as

[Markus Armbruster]

Kshitij Suri <kshitij.suri@nutanix.com> writes:

> On 16/03/22 6:55 pm, Markus Armbruster wrote:
>> Kshitij Suri <kshitij.suri@nutanix.com> writes:
>>
>>> From: "kshitij.suri" <kshitij.suri@nutanix.com>
>>>
>>> Currently screendump only supports PPM format, which is un-compressed and not
>>> standard. Added a "format" parameter to qemu monitor screendump capabilites
>>> to support PNG image capture using libpng. The param was added in QAPI schema
>>> of screendump present in ui.json along with png_save() function which converts
>>> pixman_image to PNG. HMP command equivalent was also modified to support the
>>> feature.
>>>
>>> Example usage:
>>> { "execute": "screendump", "arguments": { "filename": "/tmp/image",
>>> "format":"png" } }
>>>
>>> Resolves: https://urldefense.proofpoint.com/v2/url?u=https-3A__gitlab.com_qemu-2Dproject_qemu_-2D_issues_718&d=DwIBAg&c=s883GpUCOChKOHiocYtGcg&r=utjv19Ej9Fb0TB7_DX0o3faQ-OAm2ypPniPyqVSoj_w&m=UZZDywEeidD1LndEhKddMf_0v-jePIgMYErGImjYyvjYRJFdnv6LAHgRmZ0IpvIL&s=jc09kdvD1ULKCC9RgwWcsK6eweue3ZkyD8F9kCx5yUs&e=
>>>
>>> Signed-off-by: Kshitij Suri <kshitij.suri@nutanix.com>
>>> ---
>>> diff to v1:
>>>    - Removed repeated alpha conversion operation.
>>>    - Modified logic to mirror png conversion in vnc-enc-tight.c file.
>>>    - Added a new CONFIG_PNG parameter for libpng support.
>>>    - Changed input format to enum instead of string.
>>>    - Improved error handling.
>>>   hmp-commands.hx    |  11 ++---
>>>   monitor/hmp-cmds.c |  19 ++++++++-
>>>   qapi/ui.json       |  24 +++++++++--
>>>   ui/console.c       | 102 +++++++++++++++++++++++++++++++++++++++++++--
>>>   4 files changed, 144 insertions(+), 12 deletions(-)
>>>
>>> diff --git a/hmp-commands.hx b/hmp-commands.hx
>>> index 70a9136ac2..5eda4eeb24 100644
>>> --- a/hmp-commands.hx
>>> +++ b/hmp-commands.hx
>>> @@ -244,17 +244,18 @@ ERST
>>>   
>>>       {
>>>           .name       = "screendump",
>>> -        .args_type  = "filename:F,device:s?,head:i?",
>>> -        .params     = "filename [device [head]]",
>>> -        .help       = "save screen from head 'head' of display device 'device' "
>>> -                      "into PPM image 'filename'",
>>> +        .args_type  = "filename:F,device:s?,head:i?,format:f?",
>>> +        .params     = "filename [device [head]] [format]",
>>> +        .help       = "save screen from head 'head' of display device 'device'"
>>> +                      "in specified format 'format' as image 'filename'."
>>> +                      "Currently only 'png' and 'ppm' formats are supported.",
>>>           .cmd        = hmp_screendump,
>>>           .coroutine  = true,
>>>       },
>>>   
>>>   SRST
>>>   ``screendump`` *filename*
>>> -  Save screen into PPM image *filename*.
>>> +  Save screen as an image *filename*, with default format of PPM.
>>>   ERST
>>>   
>>>       {
>>> diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
>>> index 8c384dc1b2..9a640146eb 100644
>>> --- a/monitor/hmp-cmds.c
>>> +++ b/monitor/hmp-cmds.c
>>> @@ -1677,9 +1677,26 @@ hmp_screendump(Monitor *mon, const QDict *qdict)
>>>       const char *filename = qdict_get_str(qdict, "filename");
>>>       const char *id = qdict_get_try_str(qdict, "device");
>>>       int64_t head = qdict_get_try_int(qdict, "head", 0);
>>> +    const char *input_format  = qdict_get_str(qdict, "format");
>>>       Error *err = NULL;
>>> +    ImageFormat format;
>>>   
>>> -    qmp_screendump(filename, id != NULL, id, id != NULL, head, &err);
>>
>> The second id != NULL looks wrong.  Shouldn't it be head != NULL?

Can't: @head is not a pointer.

>> Not your patch's fault, of course.
>
> As per hmp-commands.hx input is of format [device [head]] so maybe
> works as a pair.

I looked: no, it works because it duplicates qmp_screendump()'s default.

qmp_screendump()'s behavior:

* If neither @device nor @head are present, default to console #0.

* If only @device is present, default to head 0 of the specified device.

* If both are present, default to the specified head of the specified
  device.

* If only @head is present, error out.

Ideally, we'd have hmp_screendump() pass its arguments unadulterated to
qmp_screendump(), so logic isn't duplicated.

Unfortunately, this turns out to be a bit troublesome.
qdict_get_try_int() *forces* us to supply a default value, and doesn't
tell us whether argument is present.  We'd have to use qdict_haskey()
for that:

    qmp_screendump(filename, id != NULL, id, qdict_haskey("head"), head,
                   &err);

The current code instead replaces case "only @device is present" by
"both are present".  Works, because the default it uses matches the one
in qmp_screendump().

I find this less obvious, but I'm not sure it's worth patching.

Note that case "only @head is present" isn't possible because the
arguments are positional.

>                  Is it alright if I investigate and send in another patch
> after this?

Let's not bother.