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genode/repos/demo/include/scout_gfx/icon_painter.h
Norman Feske ed774253b6 demo: fix corner case in scout_gfx/icon_painter.h 
The original version of the icon painter would reach beyong the
texture boundaries for textures of even width and height, and when
painting an icon with the width or height of the texture.

In this case, p3 would be set to the same value as p2. However, the code
expects p3 to lie within the middle rectangle. However, in this corner
case, the middle rectangle is actually empty. So no pixel can lie within
it. Hence, p3 is positioned by one pixel to the left outside the middle
rectangle, which violates the assumptions when calculating the clipping
and texture offsets. The patch fixes the problem by reducing the size of
the right column by one pixel. This ensures that exists always a
non-zero middle rectangle.
2015-11-27 12:18:53 +01:00

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/*
* \brief Functor for drawing an icon onto a surface
* \author Norman Feske
* \date 2005-10-24
*/
/*
* Copyright (C) 2006-2013 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU General Public License version 2.
*/
#ifndef _INCLUDE__SCOUT_GFX__ICON_PAINTER_H_
#define _INCLUDE__SCOUT_GFX__ICON_PAINTER_H_
#include <os/texture.h>
class Icon_painter
{
private:
/*
* An Icon has the following layout:
*
* P1---+--------+----+
* | cs | hs | cs | top row
* +----P2-------+----+
* | | | |
* | vs | | vs | mid row
* | | | |
* +----+--------P3---+
* | cs | hs | cs | low row
* +------------------P4
*
* cs ... corner slice
* hs ... horizontal slice
* vs ... vertical slice
*/
/**
* Copy pixel with alpha
*/
template <typename SPT, typename TPT>
static inline void _transfer_pixel(TPT const &src, int src_a, int alpha, SPT *dst)
{
if (src_a) {
int register a = (src_a * alpha)>>8;
if (a) *dst = SPT::mix(*dst, src, a);
}
}
/**
* Draw corner slice
*/
template <typename SPT, typename TPT>
static void _draw_cslice(TPT const *src, unsigned char const *src_a,
unsigned src_pitch, int alpha, SPT *dst,
unsigned dst_pitch, int w, int h)
{
for (int j = 0; j < h; j++) {
TPT const *s = src;
unsigned char const *sa = src_a;
SPT *d = dst;
for (int i = 0; i < w; i++, s++, sa++, d++)
_transfer_pixel(*s, *sa, alpha, d);
src += src_pitch, src_a += src_pitch, dst += dst_pitch;
}
}
/**
* Draw horizontal slice
*/
template <typename SPT, typename TPT>
static void _draw_hslice(TPT const *src, unsigned char const *src_a,
int src_pitch, int alpha, SPT *dst,
int dst_pitch, int w, int h)
{
for (int j = 0; j < h; j++) {
TPT s = *src;
int sa = *src_a;
SPT *d = dst;
for (int i = 0; i < w; i++, d++)
_transfer_pixel(s, sa, alpha, d);
src += src_pitch, src_a += src_pitch, dst += dst_pitch;
}
}
/**
* Draw vertical slice
*/
template <typename SPT, typename TPT>
static void _draw_vslice(TPT const *src, unsigned char const *src_a,
int src_pitch, int alpha, SPT *dst,
int dst_pitch, int w, int h)
{
for (int i = 0; i < w; i++) {
TPT s = *src;
int sa = *src_a;
SPT *d = dst;
for (int j = 0; j < h; j++, d += dst_pitch)
_transfer_pixel(s, sa, alpha, d);
src += 1, src_a += 1, dst += 1;
}
}
/**
* Draw center slice
*/
template <typename SPT, typename TPT>
static void _draw_center(TPT const *src, unsigned char const *src_a,
int src_pitch, int alpha, SPT *dst,
int dst_pitch, int w, int h)
{
TPT s = *src;
int sa = *src_a;
for (int j = 0; j < h; j++, dst += dst_pitch) {
SPT *d = dst;
for (int i = 0; i < w; i++, d++)
_transfer_pixel(s, sa, alpha, d);
}
}
/**
* Clip rectangle against clipping region
*
* The out parameters are the resulting x/y offsets and the
* visible width and height.
*
* \return 1 if rectangle intersects with clipping region,
* 0 otherwise
*/
static inline int _clip(int px1, int py1, int px2, int py2,
int cx1, int cy1, int cx2, int cy2,
int *out_x, int *out_y, int *out_w, int *out_h)
{
/* determine intersection of rectangle and clipping region */
int x1 = Genode::max(px1, cx1);
int y1 = Genode::max(py1, cy1);
int x2 = Genode::min(px2, cx2);
int y2 = Genode::min(py2, cy2);
*out_w = x2 - x1 + 1;
*out_h = y2 - y1 + 1;
*out_x = x1 - px1;
*out_y = y1 - py1;
return (*out_w > 0) && (*out_h > 0);
}
public:
typedef Genode::Surface_base::Area Area;
typedef Genode::Surface_base::Rect Rect;
template <typename SPT, typename TPT>
static inline void paint(Genode::Surface<SPT> &surface, Rect rect,
Genode::Texture<TPT> const &icon, unsigned alpha)
{
SPT *addr = surface.addr();
if (!addr || (alpha == 0)) return;
int const cx1 = surface.clip().x1();
int const cy1 = surface.clip().y1();
int const cx2 = surface.clip().x2();
int const cy2 = surface.clip().y2();
unsigned const icon_w = icon.size().w(),
icon_h = icon.size().h();
/* determine point positions */
int const x1 = rect.x1();
int const y1 = rect.y1();
int const x4 = x1 + rect.w() - 1;
int const y4 = y1 + rect.h() - 1;
int const x2 = x1 + icon_w/2;
int const y2 = y1 + icon_h/2;
int const x3 = Genode::max(x4 - (int)icon_w/2 + 1, x2);
int const y3 = Genode::max(y4 - (int)icon_h/2 + 1, y2);
int const tx1 = 0;
int const ty1 = 0;
int const tx4 = icon_w - 1;
int const ty4 = icon_h - 1;
int const tx2 = icon_w/2;
int const ty2 = icon_h/2;
int const tx3 = Genode::max(tx4 - (int)icon_w/2 + 1, tx2);
int const ty3 = Genode::max(ty4 - (int)icon_h/2 + 1, ty2);
TPT const *src = icon.pixel() + icon_w*ty1;
unsigned char const *src_a = icon.alpha() + icon_w*ty1;
int dx, dy, w, h;
/*
* top row
*/
if (_clip(x1, y1, x2 - 1, y2 - 1, cx1, cy1, cx2, cy2, &dx, &dy, &w, &h))
_draw_cslice(src + tx1 + dy*icon_w + dx, src_a + tx1 + dy*icon_w + dx, icon_w, alpha,
addr + (y1 + dy)*surface.size().w() + x1 + dx, surface.size().w(), w, h);
if (_clip(x2, y1, x3 - 1, y2 - 1, cx1, cy1, cx2, cy2, &dx, &dy, &w, &h))
_draw_hslice(src + tx2 + dy*icon_w + dx, src_a + tx2 + dy*icon_w + dx, icon_w, alpha,
addr + (y1 + dy)*surface.size().w() + x2 + dx, surface.size().w(), w, h);
if (_clip(x3, y1, x4, y2 - 1, cx1, cy1, cx2, cy2, &dx, &dy, &w, &h))
_draw_cslice(src + tx3 + dy*icon_w + dx, src_a + tx3 + dy*icon_w + dx, icon_w, alpha,
addr + (y1 + dy)*surface.size().w() + x3 + dx, surface.size().w(), w, h);
/*
* mid row
*/
src = icon.pixel() + icon_w*ty2;
src_a = icon.alpha() + icon_w*ty2;
if (_clip(x1, y2, x2 - 1, y3 - 1, cx1, cy1, cx2, cy2, &dx, &dy, &w, &h))
_draw_vslice(src + tx1 + dx, src_a + tx1 + dx, icon_w, alpha,
addr + (y2 + dy)*surface.size().w() + x1 + dx, surface.size().w(), w, h);
if (_clip(x2, y2, x3 - 1, y3 - 1, cx1, cy1, cx2, cy2, &dx, &dy, &w, &h))
_draw_center(src + tx2, src_a + tx2, icon_w, alpha,
addr + (y2 + dy)*surface.size().w() + x2 + dx, surface.size().w(), w, h);
if (_clip(x3, y2, x4, y3 - 1, cx1, cy1, cx2, cy2, &dx, &dy, &w, &h))
_draw_vslice(src + tx3 + dx, src_a + tx3 + dx, icon_w, alpha,
addr + (y2 + dy)*surface.size().w() + x3 + dx, surface.size().w(), w, h);
/*
* low row
*/
src = icon.pixel() + icon_w*ty3;
src_a = icon.alpha() + icon_w*ty3;
if (_clip(x1, y3, x2 - 1, y4, cx1, cy1, cx2, cy2, &dx, &dy, &w, &h))
_draw_cslice(src + tx1 + dy*icon_w + dx, src_a + tx1 + dy*icon_w + dx, icon_w, alpha,
addr + (y3 + dy)*surface.size().w() + x1 + dx, surface.size().w(), w, h);
if (_clip(x2, y3, x3 - 1, y4, cx1, cy1, cx2, cy2, &dx, &dy, &w, &h))
_draw_hslice(src + tx2 + dy*icon_w + dx, src_a + tx2 + dy*icon_w + dx, icon_w, alpha,
addr + (y3 + dy)*surface.size().w() + x2 + dx, surface.size().w(), w, h);
if (_clip(x3, y3, x4, y4, cx1, cy1, cx2, cy2, &dx, &dy, &w, &h))
_draw_cslice(src + tx3 + dy*icon_w + dx, src_a + tx3 + dy*icon_w + dx, icon_w, alpha,
addr + (y3 + dy)*surface.size().w() + x3 + dx, surface.size().w(), w, h);
}
};
#endif /* _INCLUDE__SCOUT_GFX__ICON_PAINTER_H_ */
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