Attachment 131034 Details for Bug 100793 – Multi-monitor issue with negative extent patch

[patch] Multi-monitor issue with negative extent patch

cairo-win32-multi-monitor-patch.diff (text/plain), 5.10 KB, created by Eric Hoffman on 2017-04-26 04:22:25 UTC

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Creator: Eric Hoffman

Created: 2017-04-26 04:22:25 UTC

Size: 5.10 KB

patch

obsolete

>diff --git a/src/win32/cairo-win32-display-surface.c b/src/win32/cairo-win32-display-surface.c
>index 025b2c9eb..76ab5a1c8 100644
>--- a/src/win32/cairo-win32-display-surface.c
>+++ b/src/win32/cairo-win32-display-surface.c
>@@ -325,6 +325,8 @@ _cairo_win32_display_surface_create_for_dc (HDC             original_dc,
>     surface->win32.extents.y = 0;
>     surface->win32.extents.width = width;
>     surface->win32.extents.height = height;
>+    surface->win32.x_ofs = 0; 
>+    surface->win32.y_ofs = 0;
> 
>     surface->initial_clip_rgn = NULL;
>     surface->had_simple_clip = FALSE;
>@@ -466,7 +468,8 @@ _cairo_win32_display_surface_map_to_image (void                    *abstract_sur
> 		     surface->win32.extents.width,
> 		     surface->win32.extents.height,
> 		     surface->win32.dc,
>-		     surface->win32.extents.x, surface->win32.extents.y,
>+		     surface->win32.extents.x + surface->win32.x_ofs, /* Handling multi-monitor... */
>+		     surface->win32.extents.y + surface->win32.y_ofs, /* ... setup on Win32 */
> 		     SRCCOPY)) {
> 	    status = _cairo_error (CAIRO_STATUS_DEVICE_ERROR);
> 	    goto err;
>@@ -544,11 +547,12 @@ _cairo_win32_display_surface_flush (void *abstract_surface, unsigned flags)
> 
> 	if (damage->status) {
> 	    if (!BitBlt (surface->win32.dc,
>-			 0, 0,
>+			 surface->win32.extents.x + surface->win32.x_ofs, /* Handling multi-monitor... */
>+			 surface->win32.extents.y + surface->win32.y_ofs, /* ... setup on Win32 */
> 			 surface->win32.extents.width,
> 			 surface->win32.extents.height,
> 			 fallback->win32.dc,
>-			 0, 0,
>+			 fallback->win32.extents.x, fallback->win32.extents.y,
> 			 SRCCOPY))
> 		status = _cairo_win32_print_gdi_error (__FUNCTION__);
> 	} else if (damage->region) {
>@@ -561,7 +565,8 @@ _cairo_win32_display_surface_flush (void *abstract_surface, unsigned flags)
> 			rect.x, rect.y,
> 			rect.width, rect.height));
> 		if (!BitBlt (surface->win32.dc,
>-			     rect.x, rect.y,
>+			     rect.x + surface->win32.x_ofs, /* Handling multi-monitor... */
>+			     rect.y + surface->win32.y_ofs, /* ... setup on Win32 */
> 			     rect.width, rect.height,
> 			     fallback->win32.dc,
> 			     rect.x, rect.y,
>@@ -628,6 +633,35 @@ _cairo_win32_save_initial_clip (HDC hdc, cairo_win32_display_surface_t *surface)
>     surface->win32.extents.width = rect.right - rect.left;
>     surface->win32.extents.height = rect.bottom - rect.top;
> 
>+    /* On multi-monitor setup, under Windows, the primary monitor always
>+     * have origin (0,0).  Any monitors that extends to the left or above 
>+     * will have coordinates in the negative range.  Take this into
>+     * account, by forcing our Win32 surface to start at extent (0,0) and 
>+     * using a device offset.  Cairo does not handle extents with negative 
>+     * offsets.
>+     */ 
>+    surface->win32.x_ofs = 0;
>+    surface->win32.y_ofs = 0;
>+    if ((surface->win32.extents.x < 0) ||
>+	(surface->win32.extents.y < 0)) {
>+	/* Negative offsets occurs for (and ONLY for) the desktop DC (virtual
>+	 * desktop), when a monitor extend to the left or above the primary 
>+	 * monitor. 
>+	 *  
>+	 * More info @ https://www.microsoft.com/msj/0697/monitor/monitor.aspx 
>+	 *  
>+	 * Note that any other DC, including memory DC created with 
>+	 * CreateCompatibleDC(<virtual desktop DC>) will have extents in the
>+	 * positive range.  This will be taken into account later when we perform 
>+	 * raster operations between the DC (may have to perform offset 
>+	 * translation).
>+	 */
>+	surface->win32.x_ofs = surface->win32.extents.x;
>+	surface->win32.y_ofs = surface->win32.extents.y;
>+	surface->win32.extents.x = 0;
>+	surface->win32.extents.y = 0;
>+    }
>+
>     surface->initial_clip_rgn = NULL;
>     surface->had_simple_clip = FALSE;
> 
>diff --git a/src/win32/cairo-win32-private.h b/src/win32/cairo-win32-private.h
>index 6fdf96f87..87ef38521 100644
>--- a/src/win32/cairo-win32-private.h
>+++ b/src/win32/cairo-win32-private.h
>@@ -100,6 +100,24 @@ typedef struct _cairo_win32_surface {
>      * that match bounds of the clipped region.
>      */
>     cairo_rectangle_int_t extents;
>+
>+    /* Offset added to extents, used when the extents start with a negative
>+     * offset, which occur on Windows for, and only for, desktop DC.  This 
>+     * occurs when you have multiple monitors, and at least one monitor 
>+     * extends to the left, or above, the primaty monitor.  The primary 
>+     * monitor on Windows always start with offset (0,0), and any other points 
>+     * to the left, or above, have negative offset.  So the 'desktop DC' is 
>+     * in fact a 'virtual desktop' which can start with extents in the negative 
>+     * range. 
>+     *  
>+     * Why use new variables, and not the device transform?  Simply because since 
>+     * the device transform functions are exposed, a lot of 3rd party libraries 
>+     * simply overwrite those, disregarding the prior content, instead of actually 
>+     * adding the offset.  GTK for example simply reset the device transform of the 
>+     * desktop cairo surface to zero.  So make some private member variables for 
>+     * this, which will not be fiddled with externally. 
>+     */
>+    int x_ofs, y_ofs;
> } cairo_win32_surface_t;
> #define to_win32_surface(S) ((cairo_win32_surface_t *)(S))
>

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Attachments on bug 100793: 131034 | 131112 | 131113

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