From 09238a9bb536982e79b60a264b1d8a4fc0302975 Mon Sep 17 00:00:00 2001
From: wm4 <wm4@nowhere>
Date: Fri, 2 Dec 2016 15:26:45 +0100
Subject: vo_opengl: don't rely on viewport to contain window dimensions

Apparently we don't always set the viewport to window dimensions
anymore, e.g. if nothing is actually rendered. This means the viewport
can contain old values.

The window screenshot code uses the viewport values to guess the default
framebuffer dimensions. With --force-window --idle --no-osc (which draws
nothing and issues a glClear() command only), taking a screenshot would
yield an image with the wrong size and possibly garbage in it. Fix this
by explicitly passing the currently known window dimensions. Abusing the
values stored in the viewport was questionable anyway.
---
 video/out/opengl/utils.c | 11 ++++-------
 video/out/opengl/utils.h |  2 +-
 video/out/vo_opengl.c    |  3 ++-
 3 files changed, 7 insertions(+), 9 deletions(-)

(limited to 'video')

diff --git a/video/out/opengl/utils.c b/video/out/opengl/utils.c
index 6c879fd535..aa43728cb8 100644
--- a/video/out/opengl/utils.c
+++ b/video/out/opengl/utils.c
@@ -100,13 +100,11 @@ void gl_upload_tex(GL *gl, GLenum target, GLenum format, GLenum type,
     gl->PixelStorei(GL_UNPACK_ALIGNMENT, 4);
 }
 
-mp_image_t *gl_read_window_contents(GL *gl)
+mp_image_t *gl_read_window_contents(GL *gl, int w, int h)
 {
     if (gl->es)
         return NULL; // ES can't read from front buffer
-    GLint vp[4]; //x, y, w, h
-    gl->GetIntegerv(GL_VIEWPORT, vp);
-    mp_image_t *image = mp_image_alloc(IMGFMT_RGB24, vp[2], vp[3]);
+    mp_image_t *image = mp_image_alloc(IMGFMT_RGB24, w, h);
     if (!image)
         return NULL;
     gl->BindFramebuffer(GL_FRAMEBUFFER, gl->main_fb);
@@ -114,9 +112,8 @@ mp_image_t *gl_read_window_contents(GL *gl)
     gl->PixelStorei(GL_PACK_ALIGNMENT, 1);
     gl->ReadBuffer(obj);
     //flip image while reading (and also avoid stride-related trouble)
-    for (int y = 0; y < vp[3]; y++) {
-        gl->ReadPixels(vp[0], vp[1] + vp[3] - y - 1, vp[2], 1,
-                       GL_RGB, GL_UNSIGNED_BYTE,
+    for (int y = 0; y < h; y++) {
+        gl->ReadPixels(0, h - y - 1, w, 1, GL_RGB, GL_UNSIGNED_BYTE,
                        image->planes[0] + y * image->stride[0]);
     }
     gl->PixelStorei(GL_PACK_ALIGNMENT, 4);
diff --git a/video/out/opengl/utils.h b/video/out/opengl/utils.h
index 33c2daa5be..f4e522cdf7 100644
--- a/video/out/opengl/utils.h
+++ b/video/out/opengl/utils.h
@@ -30,7 +30,7 @@ void gl_upload_tex(GL *gl, GLenum target, GLenum format, GLenum type,
                    const void *dataptr, int stride,
                    int x, int y, int w, int h);
 
-mp_image_t *gl_read_window_contents(GL *gl);
+mp_image_t *gl_read_window_contents(GL *gl, int w, int h);
 
 const char* mp_sampler_type(GLenum texture_target);
 
diff --git a/video/out/vo_opengl.c b/video/out/vo_opengl.c
index 508ba9cda9..7f65a1eafc 100644
--- a/video/out/vo_opengl.c
+++ b/video/out/vo_opengl.c
@@ -272,7 +272,8 @@ static int control(struct vo *vo, uint32_t request, void *data)
         return VO_NOTIMPL;
     }
     case VOCTRL_SCREENSHOT_WIN: {
-        struct mp_image *screen = gl_read_window_contents(p->gl);
+        struct mp_image *screen =
+            gl_read_window_contents(p->gl, vo->dwidth, vo->dheight);
         if (!screen)
             break; // redirect to backend
         // set image parameters according to the display, if possible
-- 
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