Making a sample for shadow maps for more intensive development

include/utils/SkShadowPaintFilterCanvas.h

Index: include/utils/SkShadowPaintFilterCanvas.h
diff --git a/include/utils/SkShadowPaintFilterCanvas.h b/include/utils/SkShadowPaintFilterCanvas.h
new file mode 100644
index 0000000000000000000000000000000000000000..a242f2e2c7f7506276899f68db94751cf5b16790
--- /dev/null
+++ b/include/utils/SkShadowPaintFilterCanvas.h
@@ -0,0 +1,230 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkShadowPaintFilterCanvas_DEFINED
+#define SkShadowPaintFilterCanvas_DEFINED

[jvanverth1, 2016/08/02 17:43:33]

Does this need to be inside an #ifdef SK_EXPERIMENTAL_SHADOWING block?

[vjiaoblack, 2016/08/03 14:04:21]

Hmm... I guess it would make sense for it to be

+
+#include "SkNWayCanvas.h"
+#include "SkTLazy.h"
+#include "SkLights.h"
+#include "SkPaintFilterCanvas.h"
+#include "SkCanvas.h"
+
+/** \class SkPaintFilterCanvas
+
+    A utility proxy base class for implementing shadow maps.
+*/
+
+/*  We override the onFilter method to draw depths into the canvas
+ *  depending on the current draw depth of the canvas, throwing out
+ *  the actual draw color.
+ */
+class SkShadowPaintFilterCanvas : public SkPaintFilterCanvas {
+public:
+
+    sk_sp<SkLights> getLights() {
+        return INHERITED::getLights();
+    }
+

[robertphillips, 2016/08/02 16:05:06]

Will this fit on one line?

[vjiaoblack, 2016/08/03 14:04:21]

Yeah, but I moved some of the code around and this should now be a non-issue

+    SkShadowPaintFilterCanvas(SkCanvas *canvas)
+            : SkPaintFilterCanvas(canvas) { }
+
+    // TODO use a shader instead
+    bool onFilter(SkTCopyOnFirstWrite<SkPaint>* paint, Type type) const override {
+        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;
+    }
+
+    void onDrawPicture(const SkPicture *picture, const SkMatrix *matrix, const SkPaint *paint) {
+        SkTCopyOnFirstWrite<SkPaint> filteredPaint(paint);
+        if (onFilter(&filteredPaint, kPicture_Type))
+            SkCanvas::onDrawPicture(picture, matrix, filteredPaint);
+    }
+
+    void updateMatrix() {
+        save();
+

[robertphillips, 2016/08/02 16:05:06]

Shouldn't this now read something like:

// The user needs to update the lights so that ...

?

[vjiaoblack, 2016/08/03 14:04:21]

Done.

+        // TODO which light do we set?
+        if (this->fLights->light(0).type() != SkLights::Light::kAmbient_LightType) {
+            SkVector3 lightDir = this->fLights->light(0).dir();
+            SkScalar x = lightDir.fX * this->getZ();
+            SkScalar y = lightDir.fY * this->getZ();
+
+            this->translate(x, y);
+        }
+
+    }
+

[robertphillips, 2016/08/02 16:05:06]

What happened to all the overrides?

[vjiaoblack, 2016/08/03 14:04:21]

Currently, I can't have them. (after the refactoring this out into a cpp and an
h)

+    void onDrawPaint(const SkPaint &paint) {
+        updateMatrix();
+        this->INHERITED::onDrawPaint(paint);
+        restore();
+    }
+
+    void onDrawPoints(PointMode mode, size_t count, const SkPoint pts[],
+                      const SkPaint &paint) {
+        updateMatrix();
+        this->INHERITED::onDrawPoints(mode, count, pts, paint);
+        restore();
+    }
+
+    void onDrawRect(const SkRect &rect, const SkPaint &paint) {
+        updateMatrix();
+        this->INHERITED::onDrawRect(rect, paint);
+        restore();
+    }
+
+    void onDrawRRect(const SkRRect &rrect, const SkPaint &paint) {
+        updateMatrix();
+        this->INHERITED::onDrawRRect(rrect, paint);
+        restore();
+    }
+
+    void onDrawDRRect(const SkRRect &outer, const SkRRect &inner,
+                      const SkPaint &paint) {
+        updateMatrix();
+        this->INHERITED::onDrawDRRect(outer, inner, paint);
+        restore();
+    }
+
+    void onDrawOval(const SkRect &rect, const SkPaint &paint) {
+        updateMatrix();
+        this->INHERITED::onDrawOval(rect, paint);
+        restore();
+    }
+
+    void onDrawPath(const SkPath &path, const SkPaint &paint) {
+        updateMatrix();
+        this->INHERITED::onDrawPath(path, paint);
+        restore();
+    }
+
+    void onDrawBitmap(const SkBitmap &bm, SkScalar left, SkScalar top,
+                      const SkPaint *paint) {
+        updateMatrix();
+        this->INHERITED::onDrawBitmap(bm, left, top, paint);
+        restore();
+    }
+
+    void onDrawBitmapRect(const SkBitmap &bm, const SkRect *src, const SkRect &dst,
+                          const SkPaint *paint, SrcRectConstraint constraint) {
+        updateMatrix();
+        this->INHERITED::onDrawBitmapRect(bm, src, dst, paint, constraint);
+        restore();
+    }
+
+    void onDrawBitmapNine(const SkBitmap &bm, const SkIRect &center,
+                          const SkRect &dst, const SkPaint *paint) {
+        updateMatrix();
+        this->INHERITED::onDrawBitmapNine(bm, center, dst, paint);
+        restore();
+    }
+
+    void onDrawImage(const SkImage *image, SkScalar left, SkScalar top,
+                     const SkPaint *paint) {
+        updateMatrix();
+        this->INHERITED::onDrawImage(image, left, top, paint);
+        restore();
+    }
+
+    void onDrawImageRect(const SkImage *image, const SkRect *src,
+                         const SkRect &dst, const SkPaint *paint,
+                         SrcRectConstraint constraint) {
+        updateMatrix();
+        this->INHERITED::onDrawImageRect(image, src, dst, paint, constraint);
+        restore();
+    }
+
+    void onDrawImageNine(const SkImage *image, const SkIRect &center,
+                         const SkRect &dst, const SkPaint *paint) {
+        updateMatrix();
+        this->INHERITED::onDrawImageNine(image, center, dst, paint);
+        restore();
+    }
+
+
+    void 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) {
+        updateMatrix();
+        this->INHERITED::onDrawVertices(vmode, vertexCount, vertices, texs, colors,
+                                        xmode, indices, indexCount, paint);
+        restore();
+    }
+
+    void onDrawPatch(const SkPoint cubics[], const SkColor colors[],
+                     const SkPoint texCoords[], SkXfermode *xmode,
+                     const SkPaint &paint) {
+        updateMatrix();
+        this->INHERITED::onDrawPatch(cubics, colors, texCoords, xmode, paint);
+        restore();
+    }
+
+    void onDrawText(const void *text, size_t byteLength, SkScalar x, SkScalar y,
+                    const SkPaint &paint) {
+        updateMatrix();
+        this->INHERITED::onDrawText(text, byteLength, x, y, paint);
+        restore();
+    }
+
+    void onDrawPosText(const void *text, size_t byteLength, const SkPoint pos[],
+                       const SkPaint &paint) {
+        updateMatrix();
+        this->INHERITED::onDrawPosText(text, byteLength, pos, paint);
+        restore();
+    }
+
+    void onDrawPosTextH(const void *text, size_t byteLength, const SkScalar xpos[],
+                        SkScalar constY, const SkPaint &paint) {
+        updateMatrix();
+        this->INHERITED::onDrawPosTextH(text, byteLength, xpos, constY, paint);
+        restore();
+    }
+
+    void onDrawTextOnPath(const void *text, size_t byteLength, const SkPath &path,
+                          const SkMatrix *matrix, const SkPaint &paint) {
+        updateMatrix();
+        this->INHERITED::onDrawTextOnPath(text, byteLength, path, matrix, paint);
+        restore();
+    }
+
+    void onDrawTextRSXform(const void *text, size_t byteLength,
+                           const SkRSXform xform[], const SkRect *cull,
+                           const SkPaint &paint) {
+        updateMatrix();
+        this->INHERITED::onDrawTextRSXform(text, byteLength, xform, cull, paint);
+        restore();
+    }
+
+    void onDrawTextBlob(const SkTextBlob *blob, SkScalar x, SkScalar y, const SkPaint &paint) {
+        updateMatrix();
+        this->INHERITED::onDrawTextBlob(blob, x, y, paint);
+        restore();
+    }
+
+private:
+    typedef SkPaintFilterCanvas INHERITED;

[robertphillips, 2016/08/02 16:05:06]

extra '\n' here ?

[vjiaoblack, 2016/08/03 14:04:21]

Done.

+
+};
+
+
+#endif