Making a sample for shadow maps for more intensive development

src/utils/SkShadowPaintFilterCanvas.cpp

+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkPathEffect.h"
+#include "SkShadowPaintFilterCanvas.h"
+
+#ifdef SK_EXPERIMENTAL_SHADOWING
+
+SkShadowPaintFilterCanvas::SkShadowPaintFilterCanvas(SkCanvas *canvas)
+        : SkPaintFilterCanvas(canvas) { }
+
+// TODO use a shader instead
+bool SkShadowPaintFilterCanvas::onFilter(SkTCopyOnFirstWrite<SkPaint>* paint, Type type) const {
+    if (*paint) {
+        int z = this->getZ();
+        SkASSERT(z <= 0xFF && z >= 0x00);
+
+        SkPaint newPaint;
+        newPaint.setPathEffect(sk_ref_sp<SkPathEffect>((*paint)->getPathEffect()));
+
+        SkColor color = 0xFF000000; // init color to opaque black
+        color |= z; // Put the index into the blue component
+        newPaint.setColor(color);
+
+        *paint->writable() = newPaint;
+    }
+
+    return true;
+}
+
+SkISize SkShadowPaintFilterCanvas::ComputeDepthMapSize(const SkLights::Light& light, int maxDepth,
+                                                       int width, int height) {
+    SkASSERT(light.type() != SkLights::Light::kAmbient_LightType);
+    int dMapWidth = SkMin32(maxDepth * fabs(light.dir().fX) + width,
+                            width * 2);
+    int dMapHeight = SkMin32(maxDepth * fabs(light.dir().fY) + height,
+                             height * 2);
+    return SkISize::Make(dMapWidth, dMapHeight);
+}
+
+
+void SkShadowPaintFilterCanvas::onDrawPicture(const SkPicture *picture, const SkMatrix *matrix,
+                                              const SkPaint *paint) {
+    SkTCopyOnFirstWrite<SkPaint> filteredPaint(paint);
+    if (this->onFilter(&filteredPaint, kPicture_Type)) {
+        SkCanvas::onDrawPicture(picture, matrix, filteredPaint);
+    }
+}
+
+void SkShadowPaintFilterCanvas::updateMatrix() {
+    this->save();
+
+    //  It is up to the user to set the 0th light in fLights to
+    //  the light the want to render the depth map with.
+    if (this->fLights->light(0).type() != SkLights::Light::kAmbient_LightType) {
+        const SkVector3& lightDir = this->fLights->light(0).dir();
+        SkScalar x = lightDir.fX * this->getZ();
+        SkScalar y = lightDir.fY * this->getZ();
+
+        this->translate(x, y);
+    }
+}
+
+void SkShadowPaintFilterCanvas::onDrawPaint(const SkPaint &paint) {
+    this->updateMatrix();
+    this->INHERITED::onDrawPaint(paint);
+    this->restore();
+}
+
+void SkShadowPaintFilterCanvas::onDrawPoints(PointMode mode, size_t count, const SkPoint pts[],
+                                             const SkPaint &paint) {
+    this->updateMatrix();
+    this->INHERITED::onDrawPoints(mode, count, pts, paint);
+    this->restore();
+}
+
+void SkShadowPaintFilterCanvas::onDrawRect(const SkRect &rect, const SkPaint &paint) {
+    this->updateMatrix();
+    this->INHERITED::onDrawRect(rect, paint);
+    this->restore();
+}
+
+void SkShadowPaintFilterCanvas::onDrawRRect(const SkRRect &rrect, const SkPaint &paint) {
+    this->updateMatrix();
+    this->INHERITED::onDrawRRect(rrect, paint);
+    this->restore();
+}
+
+void SkShadowPaintFilterCanvas::onDrawDRRect(const SkRRect &outer, const SkRRect &inner,
+                  const SkPaint &paint) {
+    this->updateMatrix();
+    this->INHERITED::onDrawDRRect(outer, inner, paint);
+    this->restore();
+}
+
+void SkShadowPaintFilterCanvas::onDrawOval(const SkRect &rect, const SkPaint &paint) {
+    this->updateMatrix();
+    this->INHERITED::onDrawOval(rect, paint);
+    this->restore();
+}
+
+void SkShadowPaintFilterCanvas::onDrawPath(const SkPath &path, const SkPaint &paint) {
+    this->updateMatrix();
+    this->INHERITED::onDrawPath(path, paint);
+    this->restore();
+}
+
+void SkShadowPaintFilterCanvas::onDrawBitmap(const SkBitmap &bm, SkScalar left, SkScalar top,
+                                             const SkPaint *paint) {
+    this->updateMatrix();
+    this->INHERITED::onDrawBitmap(bm, left, top, paint);
+    this->restore();
+}
+
+void SkShadowPaintFilterCanvas::onDrawBitmapRect(const SkBitmap &bm, const SkRect *src,
+                                                 const SkRect &dst, const SkPaint *paint,
+                                                 SrcRectConstraint constraint) {
+    this->updateMatrix();
+    this->INHERITED::onDrawBitmapRect(bm, src, dst, paint, constraint);
+    this->restore();
+}
+
+void SkShadowPaintFilterCanvas::onDrawBitmapNine(const SkBitmap &bm, const SkIRect &center,
+                                                 const SkRect &dst, const SkPaint *paint) {
+    this->updateMatrix();
+    this->INHERITED::onDrawBitmapNine(bm, center, dst, paint);
+    this->restore();
+}
+
+void SkShadowPaintFilterCanvas::onDrawImage(const SkImage *image, SkScalar left,
+                                            SkScalar top, const SkPaint *paint) {
+    this->updateMatrix();
+    this->INHERITED::onDrawImage(image, left, top, paint);
+    this->restore();
+}
+
+void SkShadowPaintFilterCanvas::onDrawImageRect(const SkImage *image, const SkRect *src,
+                                                const SkRect &dst, const SkPaint *paint,
+                                                SrcRectConstraint constraint) {
+    this->updateMatrix();
+    this->INHERITED::onDrawImageRect(image, src, dst, paint, constraint);
+    this->restore();
+}
+
+void SkShadowPaintFilterCanvas::onDrawImageNine(const SkImage *image, const SkIRect &center,
+                                                const SkRect &dst, const SkPaint *paint) {
+    this->updateMatrix();
+    this->INHERITED::onDrawImageNine(image, center, dst, paint);
+    this->restore();
+}
+
+
+void SkShadowPaintFilterCanvas::onDrawVertices(VertexMode vmode, int vertexCount,
+                                               const SkPoint vertices[], const SkPoint texs[],
+                                               const SkColor colors[], SkXfermode *xmode,
+                                               const uint16_t indices[], int indexCount,
+                                               const SkPaint &paint) {
+    this->updateMatrix();
+    this->INHERITED::onDrawVertices(vmode, vertexCount, vertices, texs, colors,
+                                    xmode, indices, indexCount, paint);
+    this->restore();
+}
+
+void SkShadowPaintFilterCanvas::onDrawPatch(const SkPoint cubics[], const SkColor colors[],
+                                            const SkPoint texCoords[], SkXfermode *xmode,
+                                            const SkPaint &paint) {
+    this->updateMatrix();
+    this->INHERITED::onDrawPatch(cubics, colors, texCoords, xmode, paint);
+    this->restore();
+}
+
+void SkShadowPaintFilterCanvas::onDrawText(const void *text, size_t byteLength, SkScalar x,
+                                           SkScalar y, const SkPaint &paint) {
+    this->updateMatrix();
+    this->INHERITED::onDrawText(text, byteLength, x, y, paint);
+    this->restore();
+}
+
+void SkShadowPaintFilterCanvas::onDrawPosText(const void *text, size_t byteLength,
+                                              const SkPoint pos[], const SkPaint &paint) {
+    this->updateMatrix();
+    this->INHERITED::onDrawPosText(text, byteLength, pos, paint);
+    this->restore();
+}
+
+void SkShadowPaintFilterCanvas::onDrawPosTextH(const void *text, size_t byteLength,
+                                               const SkScalar xpos[],
+                                               SkScalar constY, const SkPaint &paint) {
+    this->updateMatrix();
+    this->INHERITED::onDrawPosTextH(text, byteLength, xpos, constY, paint);
+    this->restore();
+}
+
+void SkShadowPaintFilterCanvas::onDrawTextOnPath(const void *text, size_t byteLength,
+                                                 const SkPath &path, const SkMatrix *matrix,
+                                                 const SkPaint &paint) {
+    this->updateMatrix();
+    this->INHERITED::onDrawTextOnPath(text, byteLength, path, matrix, paint);
+    this->restore();
+}
+
+void SkShadowPaintFilterCanvas::onDrawTextRSXform(const void *text, size_t byteLength,
+                                                  const SkRSXform xform[], const SkRect *cull,
+                                                  const SkPaint &paint) {
+    this->updateMatrix();
+    this->INHERITED::onDrawTextRSXform(text, byteLength, xform, cull, paint);
+    this->restore();
+}
+
+void SkShadowPaintFilterCanvas::onDrawTextBlob(const SkTextBlob *blob, SkScalar x, SkScalar y,
+                                               const SkPaint &paint) {
+    this->updateMatrix();
+    this->INHERITED::onDrawTextBlob(blob, x, y, paint);
+    this->restore();
+}
+
+#endif