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.

1 files changed, 4 insertions, 7 deletions

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);