Various scroll area fixes

1 files changed, 263 insertions, 0 deletions

diff --git a/backingstore.c b/backingstore.c
new file mode 100644
index 0000000..5e040c4
--- /dev/null
+++ b/backingstore.c
@@ -0,0 +1,263 @@
+#include "backingstore.h"
+
+struct BackingStore
+{
+    GdkPixmap *pixmap;
+    GdkRegion *update_region;
+    int width;
+    int height;
+};
+
+BackingStore *
+backing_store_new (GdkWindow *window,
+		   int        width,
+		   int        height)
+{
+    BackingStore *store = g_new0 (BackingStore, 1);
+    GdkRectangle rect = { 0, 0, width, height };
+    
+    store->pixmap = gdk_pixmap_new (window, width, height, -1);
+    store->update_region = gdk_region_rectangle (&rect);
+    store->width = width;
+    store->height = height;
+
+    return store;
+}
+
+void
+backing_store_free (BackingStore *store)
+{
+    g_object_unref (store->pixmap);
+    gdk_region_destroy (store->update_region);
+    g_free (store);
+}
+
+void
+backing_store_scroll (BackingStore *store,
+		      int           dx,
+		      int           dy)
+{
+    GdkGC *gc = gdk_gc_new (store->pixmap);
+    GdkRectangle rect;
+    
+    gdk_draw_drawable (store->pixmap, gc, store->pixmap,
+		       0, 0, dx, dy,
+		       store->width, store->height);
+
+    gdk_region_offset (store->update_region, dx, dy);
+    
+    /* Invalidate vertically */
+    rect.x = 0;
+    rect.width = store->width;
+
+    if (dy > 0)
+    {
+	rect.y = 0;
+	rect.height = dy;
+    }
+    else
+    {
+	rect.y = store->height + dy;
+	rect.height = -dy;
+    }
+
+    gdk_region_union_with_rect (store->update_region, &rect);
+    
+    /* Invalidate horizontally */
+    rect.y = 0;
+    rect.height = store->height;
+
+    if (dx > 0)
+    {
+	rect.x = 0;
+	rect.width = dx;
+    }
+    else
+    {
+	rect.x = store->width + dx;
+	rect.width = -dx;
+    }
+
+    gdk_region_union_with_rect (store->update_region, &rect);
+}
+
+static void
+print_region (const char *header, GdkRegion *region)
+{
+    GdkRectangle *rects;
+    int n_rects;
+    int i;
+    
+    g_print ("%s\n", header);
+    
+    gdk_region_get_rectangles (region, &rects, &n_rects);
+    for (i = 0; i < n_rects; ++i)
+    {
+	GdkRectangle *rect = &(rects[i]);
+	g_print ("  %d %d %d %d\n",
+		 rect->x, rect->y, rect->width, rect->height);
+    }
+
+    g_free (rects);
+}
+
+void
+backing_store_invalidate_rect (BackingStore *store,
+			       GdkRectangle *rect)
+{
+    g_return_if_fail (store != NULL);
+    g_return_if_fail (rect != NULL);
+    
+    gdk_region_union_with_rect (store->update_region, rect);
+}
+
+void
+backing_store_invalidate_region (BackingStore *store,
+				 GdkRegion    *region)
+{
+    g_return_if_fail (store != NULL);
+    g_return_if_fail (region != NULL);
+    
+    gdk_region_union (store->update_region, region);
+}
+
+void
+backing_store_invalidate_all (BackingStore *store)
+{
+    GdkRectangle rect;
+
+    g_return_if_fail (store != NULL);
+    
+    gdk_region_destroy (store->update_region);
+    
+    rect.x = 0;
+    rect.y = 0;
+    rect.width = store->width;
+    rect.height = store->height;
+
+    store->update_region = gdk_region_rectangle (&rect);
+}
+
+static void
+simple_draw_drawable (GdkDrawable *dst,
+		      GdkDrawable *src,
+		      int	   src_x,
+		      int	   src_y,
+		      int          dst_x,
+		      int          dst_y,
+		      int          width,
+		      int          height)
+{
+    GdkGC *gc = gdk_gc_new (dst);
+
+    gdk_draw_drawable (dst, gc, src, src_x, src_y, dst_x, dst_y, width, height);
+
+    g_object_unref (gc);
+}
+
+void
+backing_store_resize (BackingStore    *store,
+		      int              width,
+		      int              height)
+{
+    GdkPixmap *pixmap;
+    GdkRegion *old, *invalid;
+    GdkRectangle r;
+
+    width = MAX (width, 1);
+    height = MAX (height, 1);
+
+    pixmap = gdk_pixmap_new (store->pixmap, width, height, -1);
+    
+    /* Unfortunately we don't know in which direction we were resized,
+     * so we just assume we were dragged from the south-east corner.
+     *
+     * Although, maybe we could get the root coordinates of the input-window?
+     * That might just work, actually. We need to make sure metacity uses
+     * static gravity for the window before this will be useful.
+     */
+    simple_draw_drawable (pixmap, store->pixmap, 0, 0, 0, 0, -1, -1);
+
+    g_object_unref (store->pixmap);
+
+    store->pixmap = pixmap;
+
+    r.x = r.y = 0;
+    r.height = store->height;
+    r.width = store->width;
+    
+    old = gdk_region_rectangle (&r);
+    
+    store->width = width;
+    store->height = height;
+
+    r.height = store->height;
+    r.width = store->width;
+    
+    invalid = gdk_region_rectangle (&r);
+
+    gdk_region_subtract (invalid, old);
+
+    backing_store_invalidate_region (store, invalid);
+
+    gdk_region_destroy (old);
+    gdk_region_destroy (invalid);
+}
+
+
+static void
+cclip_to_region (cairo_t *cr, GdkRegion *region)
+{
+    int n_rects;
+    GdkRectangle *rects;
+
+    gdk_region_get_rectangles (region, &rects, &n_rects);
+
+    cairo_new_path (cr);
+    while (n_rects--)
+    {
+	GdkRectangle *rect = &(rects[n_rects]);
+
+	cairo_rectangle (cr, rect->x, rect->y, rect->width, rect->height);
+    }
+    cairo_clip (cr);
+
+    g_free (rects);
+}
+
+void
+backing_store_draw (BackingStore *store, 
+		    GdkDrawable  *dest,
+		    GdkRegion    *clip,
+		    int           dest_x,
+		    int           dest_y)
+{
+    GdkGC *gc = gdk_gc_new (dest);
+
+    gdk_gc_set_clip_region (gc, clip);
+
+    gdk_draw_drawable (dest, gc, store->pixmap,
+		       0, 0, dest_x, dest_y, store->width, store->height);
+    g_object_unref (gc);
+}
+
+void
+backing_store_process_updates (BackingStore       *store,
+			       BackingPaintFunc    func,
+			       gpointer            data)
+{
+    cairo_t *cr = gdk_cairo_create (store->pixmap);
+    GdkRegion *region = store->update_region;
+    store->update_region = gdk_region_new ();
+
+    cclip_to_region (cr, region);
+
+    cairo_set_source_rgb (cr, g_random_double(), 0, 0);
+
+    cairo_paint (cr);
+    
+    func (cr, region, data);
+
+    gdk_region_destroy (region);
+    cairo_destroy (cr);
+}