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/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
/*
* Utilities for use with Cogl
*
* Copyright 2010 Red Hat, Inc.
* Copyright 2010 Intel Corporation
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include "config.h"
#include "compositor/clutter-utils.h"
#include <math.h>
/* This file uses pixel-aligned region computation to determine what
* can be clipped out. This only really works if everything is aligned
* to the pixel grid - not scaled or rotated and at integer offsets.
*
* (This could be relaxed - if we turned off filtering for unscaled
* windows then windows would be, by definition aligned to the pixel
* grid. And for rectangular windows without a shape, the outline that
* we draw for an unrotated window is always a rectangle because we
* don't use antialasing for the window boundary - with or without
* filtering, with or without a scale. But figuring out exactly
* what pixels will be drawn by the graphics system in these cases
* gets tricky, so we just go for the easiest part - no scale,
* and at integer offsets.)
*
* The way we check for pixel-aligned is by looking at the
* transformation into screen space of the allocation box of an actor
* and and checking if the corners are "close enough" to integral
* pixel values.
*/
/* The definition of "close enough" to integral pixel values is
* equality when we convert to 24.8 fixed-point.
*/
static inline int
round_to_fixed (float x)
{
return roundf (x * 256);
}
/* Help macros to scale from OpenGL <-1,1> coordinates system to
* window coordinates ranging [0,window-size]. Borrowed from clutter-utils.c
*/
#define MTX_GL_SCALE_X(x,w,v1,v2) ((((((x) / (w)) + 1.0f) / 2.0f) * (v1)) + (v2))
#define MTX_GL_SCALE_Y(y,w,v1,v2) ((v1) - (((((y) / (w)) + 1.0f) / 2.0f) * (v1)) + (v2))
/* This helper function checks if (according to our fixed point precision)
* the vertices @verts form a box of width @widthf and height @heightf
* located at integral coordinates. These coordinates are returned
* in @x_origin and @y_origin.
*/
gboolean
meta_actor_vertices_are_untransformed (ClutterVertex *verts,
float widthf,
float heightf,
int *x_origin,
int *y_origin)
{
int width, height;
int v0x, v0y, v1x, v1y, v2x, v2y, v3x, v3y;
int x, y;
width = round_to_fixed (widthf); height = round_to_fixed (heightf);
v0x = round_to_fixed (verts[0].x); v0y = round_to_fixed (verts[0].y);
v1x = round_to_fixed (verts[1].x); v1y = round_to_fixed (verts[1].y);
v2x = round_to_fixed (verts[2].x); v2y = round_to_fixed (verts[2].y);
v3x = round_to_fixed (verts[3].x); v3y = round_to_fixed (verts[3].y);
/* Using shifting for converting fixed => int, gets things right for
* negative values. / 256. wouldn't do the same
*/
x = v0x >> 8;
y = v0y >> 8;
/* At integral coordinates? */
if (x * 256 != v0x || y * 256 != v0y)
return FALSE;
/* Not scaled? */
if (v1x - v0x != width || v2y - v0y != height)
return FALSE;
/* Not rotated/skewed? */
if (v0x != v2x || v0y != v1y ||
v3x != v1x || v3y != v2y)
return FALSE;
if (x_origin)
*x_origin = x;
if (y_origin)
*y_origin = y;
return TRUE;
}
/* Check if an actor is "untransformed" - which actually means transformed by
* at most a integer-translation. The integer translation, if any, is returned.
*/
gboolean
meta_actor_is_untransformed (ClutterActor *actor,
int *x_origin,
int *y_origin)
{
gfloat widthf, heightf;
ClutterVertex verts[4];
clutter_actor_get_size (actor, &widthf, &heightf);
clutter_actor_get_abs_allocation_vertices (actor, verts);
return meta_actor_vertices_are_untransformed (verts, widthf, heightf, x_origin, y_origin);
}
/**
* meta_actor_painting_untransformed:
* @paint_width: the width of the painted area
* @paint_height: the height of the painted area
* @x_origin: if the transform is only an integer translation
* then the X coordinate of the location of the origin under the transformation
* from drawing space to screen pixel space is returned here.
* @y_origin: if the transform is only an integer translation
* then the X coordinate of the location of the origin under the transformation
* from drawing space to screen pixel space is returned here.
*
* Determines if the current painting transform is an integer translation.
* This can differ from the result of meta_actor_is_untransformed() when
* painting an actor if we're inside a inside a clone paint. @paint_width
* and @paint_height are used to determine the vertices of the rectangle
* we check to see if the painted area is "close enough" to the integer
* transform.
*/
gboolean
meta_actor_painting_untransformed (CoglFramebuffer *fb,
int paint_width,
int paint_height,
int *x_origin,
int *y_origin)
{
CoglMatrix modelview, projection, modelview_projection;
ClutterVertex vertices[4];
float viewport[4];
int i;
cogl_framebuffer_get_modelview_matrix (fb, &modelview);
cogl_framebuffer_get_projection_matrix (fb, &projection);
cogl_matrix_multiply (&modelview_projection,
&projection,
&modelview);
vertices[0].x = 0;
vertices[0].y = 0;
vertices[0].z = 0;
vertices[1].x = paint_width;
vertices[1].y = 0;
vertices[1].z = 0;
vertices[2].x = 0;
vertices[2].y = paint_height;
vertices[2].z = 0;
vertices[3].x = paint_width;
vertices[3].y = paint_height;
vertices[3].z = 0;
cogl_framebuffer_get_viewport4fv (fb, viewport);
for (i = 0; i < 4; i++)
{
float w = 1;
cogl_matrix_transform_point (&modelview_projection, &vertices[i].x, &vertices[i].y, &vertices[i].z, &w);
vertices[i].x = MTX_GL_SCALE_X (vertices[i].x, w,
viewport[2], viewport[0]);
vertices[i].y = MTX_GL_SCALE_Y (vertices[i].y, w,
viewport[3], viewport[1]);
}
return meta_actor_vertices_are_untransformed (vertices, paint_width, paint_height, x_origin, y_origin);
}
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