first cut at rubber-sheet warping
git-svn-id: http://skia.googlecode.com/svn/trunk@401 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/samplecode/SampleWarp.cpp b/samplecode/SampleWarp.cpp
new file mode 100644
index 0000000..5e18909
--- /dev/null
+++ b/samplecode/SampleWarp.cpp
@@ -0,0 +1,211 @@
+#include "SampleCode.h"
+#include "SkView.h"
+#include "SkCanvas.h"
+#include "SkGradientShader.h"
+#include "SkPath.h"
+#include "SkRegion.h"
+#include "SkShader.h"
+#include "SkUtils.h"
+#include "SkImageDecoder.h"
+
+class Mesh {
+public:
+ Mesh();
+ ~Mesh();
+
+ Mesh& operator=(const Mesh& src);
+
+ void init(const SkRect& bounds, int rows, int cols,
+ const SkRect& texture);
+
+ int rows() const { return fRows; }
+ int cols() const { return fCols; }
+ SkPoint& pt(int row, int col) {
+ return fPts[row * (fRows + 1) + col];
+ }
+
+ void draw(SkCanvas*, const SkPaint&);
+ void drawWireframe(SkCanvas* canvas, const SkPaint& paint);
+
+private:
+ int fRows, fCols;
+ SkPoint* fPts;
+ SkPoint* fTex; // just points into fPts, not separately allocated
+ int fCount;
+ uint16_t* fIndices;
+ int fIndexCount;
+};
+
+Mesh::Mesh() : fPts(NULL), fCount(0), fIndices(NULL), fIndexCount(0) {}
+
+Mesh::~Mesh() {
+ delete[] fPts;
+ delete[] fIndices;
+}
+
+Mesh& Mesh::operator=(const Mesh& src) {
+ delete[] fPts;
+ delete[] fIndices;
+
+ fRows = src.fRows;
+ fCols = src.fCols;
+
+ fCount = src.fCount;
+ fPts = new SkPoint[fCount * 2];
+ fTex = fPts + fCount;
+ memcpy(fPts, src.fPts, fCount * 2 * sizeof(SkPoint));
+
+ delete[] fIndices;
+ fIndexCount = src.fIndexCount;
+ fIndices = new uint16_t[fIndexCount];
+ memcpy(fIndices, src.fIndices, fIndexCount * sizeof(uint16_t));
+
+ return *this;
+}
+
+void Mesh::init(const SkRect& bounds, int rows, int cols,
+ const SkRect& texture) {
+ SkASSERT(rows > 0 && cols > 0);
+
+ fRows = rows;
+ fCols = cols;
+
+ delete[] fPts;
+ fCount = (rows + 1) * (cols + 1);
+ fPts = new SkPoint[fCount * 2];
+ fTex = fPts + fCount;
+
+ delete[] fIndices;
+ fIndexCount = rows * cols * 6;
+ fIndices = new uint16_t[fIndexCount];
+
+ SkPoint* pts = fPts;
+ const SkScalar dx = bounds.width() / rows;
+ const SkScalar dy = bounds.height() / cols;
+ SkPoint* tex = fTex;
+ const SkScalar dtx = texture.width() / rows;
+ const SkScalar dty = texture.height() / cols;
+ uint16_t* idx = fIndices;
+ int index = 0;
+ for (int y = 0; y <= cols; y++) {
+ for (int x = 0; x <= rows; x++) {
+ pts->set(bounds.fLeft + x*dx, bounds.fTop + y*dy);
+ pts += 1;
+ tex->set(texture.fLeft + x*dtx, texture.fTop + y*dty);
+ tex += 1;
+
+ if (y < cols && x < rows) {
+ *idx++ = index;
+ *idx++ = index + rows + 1;
+ *idx++ = index + 1;
+
+ *idx++ = index + 1;
+ *idx++ = index + rows + 1;
+ *idx++ = index + rows + 2;
+
+ index += 1;
+ }
+ }
+ index += 1;
+ }
+}
+
+void Mesh::draw(SkCanvas* canvas, const SkPaint& paint) {
+ canvas->drawVertices(SkCanvas::kTriangles_VertexMode, fCount,
+ fPts, fTex, NULL, NULL, fIndices, fIndexCount,
+ paint);
+}
+
+void Mesh::drawWireframe(SkCanvas* canvas, const SkPaint& paint) {
+ canvas->drawVertices(SkCanvas::kTriangles_VertexMode, fCount,
+ fPts, NULL, NULL, NULL, fIndices, fIndexCount,
+ paint);
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+class WarpView : public SkView {
+ Mesh fMesh, fOrig;
+ SkBitmap fBitmap;
+public:
+ WarpView() {
+ SkBitmap bm;
+ SkImageDecoder::DecodeFile("/skimages/nytimes.png", &bm);
+ SkIRect subset = { 0, 0, 420, 420 };
+ bm.extractSubset(&fBitmap, subset);
+
+ SkRect bounds, texture;
+ texture.set(0, 0, SkIntToScalar(fBitmap.width()),
+ SkIntToScalar(fBitmap.height()));
+ bounds = texture;
+
+// fMesh.init(bounds, fBitmap.width() / 40, fBitmap.height() / 40, texture);
+ fMesh.init(bounds, 10, 10, texture);
+ fOrig = fMesh;
+ }
+
+protected:
+ // overrides from SkEventSink
+ virtual bool onQuery(SkEvent* evt) {
+ if (SampleCode::TitleQ(*evt)) {
+ SampleCode::TitleR(evt, "Warp");
+ return true;
+ }
+ return this->INHERITED::onQuery(evt);
+ }
+
+ void warp(const SkPoint& p0, const SkPoint& p1) {
+ int rows = fMesh.rows();
+ int cols = fMesh.cols();
+
+ const SkVector delta = p1 - p0;
+ for (int y = 1; y < cols; y++) {
+ for (int x = 1; x < rows; x++) {
+ const SkPoint& orig = fOrig.pt(x, y);
+ SkScalar dist = SkPoint::Distance(p0, orig);
+ dist += SkIntToScalar(1);
+ // dist = SkScalarSqrt(dist);
+ SkScalar dx = SkScalarDiv(delta.fX, dist);
+ SkScalar dy = SkScalarDiv(delta.fY, dist);
+ fMesh.pt(x, y).set(orig.fX + dx, orig.fY + dy);
+// SkDebugf("[%g %g] -> [%d %d %g] <%g %g>\n", delta.fX, delta.fY, x, y, dist, dx, dy);
+ }
+ }
+ }
+
+ virtual void onDraw(SkCanvas* canvas) {
+ canvas->drawColor(SK_ColorGRAY);
+
+ SkPaint paint;
+ paint.setFilterBitmap(true);
+ paint.setShader(SkShader::CreateBitmapShader(fBitmap,
+ SkShader::kClamp_TileMode,
+ SkShader::kClamp_TileMode))->unref();
+ fMesh.draw(canvas, paint);
+
+ paint.setShader(NULL);
+ paint.setColor(SK_ColorRED);
+ fMesh.draw(canvas, paint);
+ }
+
+ virtual SkView::Click* onFindClickHandler(SkScalar x, SkScalar y) {
+ return new Click(this);
+ }
+
+ virtual bool onClick(Click* click) {
+ this->warp(click->fOrig, click->fCurr);
+ this->inval(NULL);
+ return true;
+ }
+
+private:
+ SkIRect fBase, fRect;
+
+ typedef SkView INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+static SkView* MyFactory() { return new WarpView; }
+static SkViewRegister reg(MyFactory);
+