From 40dde59475bef1eaa7ac70786b700fb3549bb366 Mon Sep 17 00:00:00 2001 From: Manuel Stoeckl Date: Sat, 14 Jan 2023 16:55:02 -0500 Subject: [PATCH] render/gles2: use byte-aligned rows for glReadPixels Setting the GLESv2 parameter GL_PACK_ALIGNMENT to 1 ensures that the stride of the glReadPixels output matches the value computed in `pack_stride`. Since the default value of GL_PACK_ALIGNMENT is 4, this does not make a difference under normal use; but without this patch the stride can be incorrect; for example, with RGB565 buffers and screenshots of regions with odd width. --- render/gles2/renderer.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/render/gles2/renderer.c b/render/gles2/renderer.c index 6a86b183..1c8b4878 100644 --- a/render/gles2/renderer.c +++ b/render/gles2/renderer.c @@ -473,6 +473,7 @@ static bool gles2_read_pixels(struct wlr_renderer *wlr_renderer, glGetError(); // Clear the error flag unsigned char *p = (unsigned char *)data + dst_y * stride; + glPixelStorei(GL_PACK_ALIGNMENT, 1); uint32_t pack_stride = width * drm_fmt->bpp / 8; if (pack_stride == stride && dst_x == 0) { // Under these particular conditions, we can read the pixels with only @@ -480,7 +481,7 @@ static bool gles2_read_pixels(struct wlr_renderer *wlr_renderer, glReadPixels(src_x, src_y, width, height, fmt->gl_format, fmt->gl_type, p); } else { - // Unfortunately GLES2 doesn't support GL_PACK_*, so we have to read + // Unfortunately GLES2 doesn't support GL_PACK_ROW_LENGTH, so we have to read // the lines out row by row for (size_t i = 0; i < height; ++i) { uint32_t y = src_y + i;