perspshaders.cpp File Reference

#include "gm/gm.h"
#include "include/core/SkBitmap.h"
#include "include/core/SkCanvas.h"
#include "include/core/SkColor.h"
#include "include/core/SkImage.h"
#include "include/core/SkImageInfo.h"
#include "include/core/SkMatrix.h"
#include "include/core/SkPaint.h"
#include "include/core/SkPath.h"
#include "include/core/SkPoint.h"
#include "include/core/SkRect.h"
#include "include/core/SkRefCnt.h"
#include "include/core/SkScalar.h"
#include "include/core/SkShader.h"
#include "include/core/SkSize.h"
#include "include/core/SkString.h"
#include "include/core/SkSurface.h"
#include "include/core/SkTileMode.h"
#include "include/core/SkTypes.h"
#include "include/effects/SkGradientShader.h"
#include "tools/DecodeUtils.h"
#include "tools/ToolUtils.h"
#include "tools/Resources.h"

Go to the source code of this file.

Classes
class	skiagm::PerspShadersGM

Namespaces
namespace	skiagm

Functions
static sk_sp< SkImage >	make_image (SkCanvas *origCanvas, int w, int h)
static SkPath	make_path ()
	DEF_SIMPLE_GM (perspective_clip, canvas, 800, 800)

Function Documentation

DEF_SIMPLE_GM()

DEF_SIMPLE_GM	(	perspective_clip	,
		canvas	,
		800	,
		800
	)

Definition at line 207 of file perspshaders.cpp.

                                                  {
    SkPath path = make_path();
    auto shader = ToolUtils::GetResourceAsImage("images/mandrill_128.png")
                          ->makeShader(SkSamplingOptions(), SkMatrix::Scale(3, 3));
 
    SkPaint paint;
    paint.setColor({0.75, 0.75, 0.75, 1});
    canvas->drawPath(path, paint);
 
    // This is a crazy perspective matrix, derived from halfplanes3, to draw a shape where
    // part of it is "behind" the viewer, hence showing the need for "half-plane" clipping
    // when in perspective.
    SkMatrix mx;
    const SkScalar array[] = {
        -1.7866f,  1.3357f, 273.0295f,
        -1.0820f,  1.3186f, 135.5196f,
        -0.0047f, -0.0015f,  2.1485f,
    };
    mx.set9(array);
 
    paint.setShader(shader);
    canvas->concat(mx);
    canvas->drawPath(path, paint);
}

make_image()

static sk_sp< SkImage > make_image ( SkCanvas *  origCanvas, int  w, int  h  )

static

Definition at line 31 of file perspshaders.cpp.

                                                                     {
    SkImageInfo info = SkImageInfo::MakeN32Premul(w, h);
    auto        surface(ToolUtils::makeSurface(origCanvas, info));
    SkCanvas* canvas = surface->getCanvas();
 
    ToolUtils::draw_checkerboard(canvas, SK_ColorRED, SK_ColorGREEN, w / 10);
    return surface->makeImageSnapshot();
}

make_path()

static SkPath make_path ( )

static

Definition at line 188 of file perspshaders.cpp.

                          {
    SkRandom rand;
    auto rand_pt = [&rand]() {
        auto x = rand.nextF();
        auto y = rand.nextF();
        return SkPoint{x * 400, y * 400};
    };
 
    SkPath path;
    for (int i = 0; i < 4; ++i) {
        SkPoint pts[6];
        for (auto& p : pts) {
            p = rand_pt();
        }
        path.moveTo(pts[0]).quadTo(pts[1], pts[2]).quadTo(pts[3], pts[4]).lineTo(pts[5]);
    }
    return path;
}