Shape: Offscreen alpha mask with render callback

Wrap rendering of alpha shapes in a class caching the picture instances
by comparing the render function and its data.

Use this in EmojiButton to avoid countless instances of the same
triangle picture.

src/bin/xmoji/emojibutton.c

@@ -2,6 +2,7 @@
 
 #include "flowgrid.h"
 #include "flyout.h"
+#include "shape.h"
 #include "textlabel.h"
 #include "textrenderer.h"
 #include "unistr.h"
@@ -24,23 +25,18 @@ struct EmojiButton
     Object base;
     FlowGrid *flowgrid;
     Flyout *flyout;
-    xcb_pixmap_t pixmap;
-    xcb_render_picture_t pic;
+    Shape *triangle;
     xcb_render_picture_t pen;
     Color pencolor;
+    Size trianglesize;
     int selected;
 };
 
 static void destroy(void *obj)
 {
     EmojiButton *self = obj;
-    if (self->pen)
-    {
-	xcb_connection_t *c = X11Adapter_connection();
-	xcb_render_free_picture(c, self->pen);
-	xcb_render_free_picture(c, self->pic);
-	xcb_free_pixmap(c, self->pixmap);
-    }
+    if (self->pen) xcb_render_free_picture(X11Adapter_connection(), self->pen);
+    Shape_destroy(self->triangle);
     free(self);
 }
 
@@ -85,62 +81,70 @@ static void renderCallback(void *ctx, TextRenderer *renderer)
     }
 }
 
-static void prerender(EmojiButton *self, Size newSize)
+static xcb_render_picture_t renderTriangle(xcb_render_picture_t ownerpic,
+	const void *data)
 {
-    if (!self->flyout) return;
-
+    const Size *sz = data;
     xcb_connection_t *c = X11Adapter_connection();
-    xcb_render_picture_t picture = Widget_picture(self);
+    xcb_screen_t *s = X11Adapter_screen();
 
-    if (!self->pen)
-    {
-	xcb_pixmap_t p = xcb_generate_id(c);
-	CHECK(xcb_create_pixmap(c, 24, p, X11Adapter_screen()->root, 1, 1),
-		"Cannot create pen pixmap for 0x%x", (unsigned)picture);
-	self->pen = xcb_generate_id(c);
-	uint32_t repeat = XCB_RENDER_REPEAT_NORMAL;
-	CHECK(xcb_render_create_picture(c, self->pen, p,
-		    X11Adapter_rgbformat(), XCB_RENDER_CP_REPEAT, &repeat),
-		"Cannot create pen for 0x%x", (unsigned)picture);
-	Color fill = 0xffffffff;
-	xcb_rectangle_t rect = {0, 0, 1, 1};
-	CHECK(xcb_render_fill_rectangles(c, XCB_RENDER_PICT_OP_OVER,
-		    self->pen, Color_xcb(fill), 1, &rect),
-		"Canot colorize pen for 0x%x", (unsigned)picture);
-	xcb_free_pixmap(c, p);
-    }
-    if (self->pic)
-    {
-	xcb_render_free_picture(c, self->pic);
-	xcb_free_pixmap(c, self->pixmap);
-    }
-    self->pixmap = xcb_generate_id(c);
-    CHECK(xcb_create_pixmap(c, 8, self->pixmap,
-		X11Adapter_screen()->root,
-		newSize.width, newSize.height),
-	    "Cannot create triangle pixmap for 0x%x",
-	    (unsigned)picture);
-    self->pic = xcb_generate_id(c);
-    CHECK(xcb_render_create_picture(c, self->pic, self->pixmap,
-		X11Adapter_alphaformat(), 0, 0),
-	    "Cannot create triangle picture for 0x%x",
-	    (unsigned)picture);
-    Color clear = 0;
-    xcb_rectangle_t rect = { 0, 0, newSize.width, newSize.height };
+    xcb_pixmap_t tmp = xcb_generate_id(c);
+    CHECK(xcb_create_pixmap(c, 8, tmp, s->root, 1, 1),
+	    "Cannot create triangle pen pixmap for 0x%x", (unsigned)ownerpic);
+    xcb_render_picture_t pen = xcb_generate_id(c);
+    uint32_t repeat = XCB_RENDER_REPEAT_NORMAL;
+    CHECK(xcb_render_create_picture(c, pen, tmp, X11Adapter_alphaformat(),
+		XCB_RENDER_CP_REPEAT, &repeat),
+	    "Cannot create triangle pen for 0x%x", (unsigned)ownerpic);
+    xcb_free_pixmap(c, tmp);
+    Color color = 0xffffffff;
+    xcb_rectangle_t rect = {0, 0, 1, 1};
+    CHECK(xcb_render_fill_rectangles(c, XCB_RENDER_PICT_OP_OVER,
+		pen, Color_xcb(color), 1, &rect),
+	    "Cannot colorize triangle pen for 0x%x", (unsigned)ownerpic);
+
+    tmp = xcb_generate_id(c);
+    CHECK(xcb_create_pixmap(c, 8, tmp, s->root, sz->width, sz->height),
+	    "Cannot create triangle pixmap for 0x%x", (unsigned)ownerpic);
+    xcb_render_picture_t pic = xcb_generate_id(c);
+    CHECK(xcb_render_create_picture(c, pic, tmp, X11Adapter_alphaformat(),
+		0, 0),
+	    "Cannot create triangle picture for 0x%x", (unsigned)ownerpic);
+    xcb_free_pixmap(c, tmp);
+    color = 0;
+    rect.width = sz->width;
+    rect.height = sz->height;
     CHECK(xcb_render_fill_rectangles(c, XCB_RENDER_PICT_OP_SRC,
-		self->pic, Color_xcb(clear), 1, &rect),
-	    "Cannot clear triangle picture for 0x%x",
-	    (unsigned)picture);
-    uint32_t x = newSize.width << 16;
-    uint32_t y = newSize.height << 16;
+		pic, Color_xcb(color), 1, &rect),
+	    "Cannot clear triangle picture for 0x%x", (unsigned)ownerpic);
+    uint32_t x = sz->width << 16;
+    uint32_t y = sz->height << 16;
     xcb_render_triangle_t triangle = {
-	{ x - (newSize.width << 14), y },
+	{ x - (sz->width << 14), y },
 	{ x, y },
-	{ x, y - (newSize.height << 14) }
+	{ x, y - (sz->height << 14) }
     };
     CHECK(xcb_render_triangles(c, XCB_RENDER_PICT_OP_OVER,
-		self->pen, self->pic, 0, 0, 0, 1, &triangle),
-	"Cannot render fly-out indicator for 0x%x", (unsigned)picture);
+		pen, pic, 0, 0, 0, 1, &triangle),
+	"Cannot render triangle for 0x%x", (unsigned)ownerpic);
+    xcb_render_free_picture(c, pen);
+
+    return pic;
+}
+
+static void prerender(EmojiButton *self, Size newSize)
+{
+    if (self->flyout && newSize.width && newSize.height
+	    && newSize.width != self->trianglesize.width
+	    && newSize.height != self->trianglesize.height)
+    {
+	self->trianglesize = newSize;
+	Shape *triangle = Shape_create(renderTriangle,
+		sizeof self->trianglesize, &self->trianglesize);
+	if (self->triangle) Shape_destroy(self->triangle);
+	Shape_render(triangle, Widget_picture(self));
+	self->triangle = triangle;
+    }
 }
 
 static int draw(void *obj, xcb_render_picture_t picture)
@@ -151,6 +155,19 @@ static int draw(void *obj, xcb_render_picture_t picture)
     if (rc == 0 && picture && self->flyout)
     {
 	xcb_connection_t *c = X11Adapter_connection();
+	if (!self->pen)
+	{
+	    xcb_pixmap_t tmp = xcb_generate_id(c);
+	    CHECK(xcb_create_pixmap(c, 24, tmp,
+			X11Adapter_screen()->root, 1, 1),
+		    "Cannot create pen pixmap for 0x%x", (unsigned)picture);
+	    self->pen = xcb_generate_id(c);
+	    uint32_t repeat = XCB_RENDER_REPEAT_NORMAL;
+	    CHECK(xcb_render_create_picture(c, self->pen, tmp,
+			X11Adapter_rgbformat(), XCB_RENDER_CP_REPEAT, &repeat),
+		    "Cannot create pen for 0x%x", (unsigned)picture);
+	    xcb_free_pixmap(c, tmp);
+	}
 	Rect geom = Widget_geometry(self);
 	if (!self->pencolor) prerender(self, geom.size);
 	Color pencolor = Widget_color(self, COLOR_ACTIVE);
@@ -163,7 +180,7 @@ static int draw(void *obj, xcb_render_picture_t picture)
 		    "Canot colorize pen for 0x%x", (unsigned)picture);
 	}
 	CHECK(xcb_render_composite(c, XCB_RENDER_PICT_OP_OVER, self->pen,
-		    self->pic, picture, 0, 0, 0, 0,
+		    Shape_picture(self->triangle), picture, 0, 0, 0, 0,
 		    geom.pos.x, geom.pos.y, geom.size.width, geom.size.height),
 		"Cannot composite fly-out indicator on 0x%x",
 		(unsigned)picture);
@@ -210,7 +227,7 @@ static void sizeChanged(void *receiver, void *sender, void *args)
     EmojiButton *self = receiver;
     SizeChangedEventArgs *ea = args;
 
-    if (ea->newSize.width && ea->newSize.height) prerender(self, ea->newSize);
+    prerender(self, ea->newSize);
 }
 
 EmojiButton *EmojiButton_createBase(void *derived,
@@ -220,10 +237,10 @@ EmojiButton *EmojiButton_createBase(void *derived,
     CREATEBASE(Button, name, parent);
     self->flowgrid = 0;
     self->flyout = 0;
-    self->pixmap = 0;
-    self->pic = 0;
+    self->triangle = 0;
     self->pen = 0;
     self->pencolor = 0;
+    self->trianglesize = (Size){0, 0};
     self->selected = 0;
 
     Button_setBorderWidth(self, 0);

src/bin/xmoji/shape.c

@@ -0,0 +1,70 @@
+#include "shape.h"
+
+#include "x11adapter.h"
+
+#include <poser/core.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct Shape
+{
+    ShapeRenderer renderer;
+    const void *data;
+    size_t datasz;
+    xcb_render_picture_t picture;
+    unsigned refcnt;
+};
+
+static PSC_List *shapes;
+
+Shape *Shape_create(ShapeRenderer renderer, size_t datasz, const void *data)
+{
+    if (!shapes) shapes = PSC_List_create();
+    for (size_t i = 0; i < PSC_List_size(shapes); ++i)
+    {
+	Shape *shape = PSC_List_at(shapes, i);
+	if (shape->renderer == renderer && shape->datasz == datasz
+		&& !memcmp(shape->data, data, datasz))
+	{
+	    ++shape->refcnt;
+	    return shape;
+	}
+    }
+    Shape *self = PSC_malloc(sizeof *self);
+    self->renderer = renderer;
+    self->data = data;
+    self->datasz = datasz;
+    self->picture = 0;
+    self->refcnt = 1;
+    PSC_List_append(shapes, self, 0);
+    return self;
+}
+
+void Shape_render(Shape *self, xcb_render_picture_t ownerpic)
+{
+    if (self->picture) return;
+    self->picture = self->renderer(ownerpic, self->data);
+}
+
+xcb_render_picture_t Shape_picture(const Shape *self)
+{
+    return self->picture;
+}
+
+void Shape_destroy(Shape *self)
+{
+    if (!self) return;
+    if (--self->refcnt) return;
+    PSC_List_remove(shapes, self);
+    if (!PSC_List_size(shapes))
+    {
+	PSC_List_destroy(shapes);
+	shapes = 0;
+    }
+    if (self->picture)
+    {
+	xcb_render_free_picture(X11Adapter_connection(), self->picture);
+    }
+    free(self);
+}
+

src/bin/xmoji/shape.h

@@ -0,0 +1,18 @@
+#ifndef XMOJI_SHAPE_H
+#define XMOJI_SHAPE_H
+
+#include <poser/decl.h>
+#include <xcb/render.h>
+
+C_CLASS_DECL(Shape);
+
+typedef xcb_render_picture_t (*ShapeRenderer)(
+	xcb_render_picture_t ownerpic, const void *data);
+
+Shape *Shape_create(ShapeRenderer renderer,
+	size_t datasz, const void *data) ATTR_RETNONNULL;
+void Shape_render(Shape *self, xcb_render_picture_t ownerpic) CMETHOD;
+xcb_render_picture_t Shape_picture(const Shape *self) CMETHOD ATTR_PURE;
+void Shape_destroy(Shape *self);
+
+#endif

src/bin/xmoji/xmoji.mk

@@ -21,6 +21,7 @@ xmoji_MODULES=		button \
 			object \
 			pixmap \
 			scrollbox \
+			shape \
 			surface \
 			tabbox \
 			textbox \