Add matrix operations to C canvas API

src/c/sk_surface.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "sk_canvas.h"
 #include "sk_image.h"
 #include "sk_paint.h"
@@ skipping 73 matching lines @@
     if (!from_c_alphatype(cinfo.alphaType, &at)) {
         // optionally report error to client?
         return false;
     }
     if (info) {
         *info = SkImageInfo::Make(cinfo.width, cinfo.height, ct, at);
     }
     return true;
 }
 
+static void from_c_matrix(const sk_matrix_t* cmatrix, SkMatrix* matrix) {
+    if (cmatrix) {
+        matrix->setAll(cmatrix->mat[0], cmatrix->mat[1], cmatrix->mat[2],
+                       cmatrix->mat[3], cmatrix->mat[4], cmatrix->mat[5],
+                       cmatrix->mat[6], cmatrix->mat[7], cmatrix->mat[8]);
+    } else {
+        matrix->setIdentity();
+    }
+}
+
 const struct {
     sk_path_direction_t fC;
     SkPath::Direction   fSk;
 } gPathDirMap[] = {
     { CW_SK_PATH_DIRECTION,  SkPath::kCW_Direction },
     { CCW_SK_PATH_DIRECTION, SkPath::kCCW_Direction },
 };
 
 static bool from_c_path_direction(sk_path_direction_t cdir, SkPath::Direction* dir) {
     for (size_t i = 0; i < SK_ARRAY_COUNT(gPathDirMap); ++i) {
@@ skipping 209 matching lines @@
 }
 
 void sk_canvas_rotate_radians(sk_canvas_t* ccanvas, float radians) {
     AsCanvas(ccanvas)->rotate(SkRadiansToDegrees(radians));
 }
 
 void sk_canvas_skew(sk_canvas_t* ccanvas, float sx, float sy) {
     AsCanvas(ccanvas)->skew(sx, sy);
 }
 
+void sk_canvas_concat_matrix(sk_canvas_t* ccanvas, const sk_matrix_t* cmatrix) {
+    SkMatrix matrix;

[reed1, 2014/12/02 17:41:43]

can probably move the null-check to here, rather than in the converter (assuming
we want that and not to just crash/assert).

[abarth-chromium, 2014/12/02 17:43:16]

IMHO, we should crash/assert.  It seems better for the API to be strict, at
least at the beginning.  We can always loosen these things later, but they're
much harder to tighten.

+    from_c_matrix(cmatrix, &matrix);
+    AsCanvas(ccanvas)->concat(matrix);
+}
+
 void sk_canvas_draw_paint(sk_canvas_t* ccanvas, const sk_paint_t* cpaint) {
     AsCanvas(ccanvas)->drawPaint(AsPaint(*cpaint));
 }
 
 void sk_canvas_draw_rect(sk_canvas_t* ccanvas, const sk_rect_t* crect, const sk_paint_t* cpaint) {
     AsCanvas(ccanvas)->drawRect(AsRect(*crect), AsPaint(*cpaint));
 }
 
 void sk_canvas_draw_oval(sk_canvas_t* ccanvas, const sk_rect_t* crect, const sk_paint_t* cpaint) {
     AsCanvas(ccanvas)->drawOval(AsRect(*crect), AsPaint(*cpaint));
@@ skipping 79 matching lines @@
                                            const sk_color_t colors[],
                                            const float colorPos[],
                                            int colorCount,
                                            sk_shader_tilemode_t cmode,
                                            const sk_matrix_t* cmatrix) {
     SkShader::TileMode mode;
     if (!from_c_tilemode(cmode, &mode)) {
         return NULL;
     }
     SkMatrix matrix;
-    if (cmatrix) {
-        matrix.setAll(cmatrix->mat[0], cmatrix->mat[1], cmatrix->mat[2],
-                      cmatrix->mat[3], cmatrix->mat[4], cmatrix->mat[5],
-                      cmatrix->mat[6], cmatrix->mat[7], cmatrix->mat[8]);
-    } else {
-        matrix.setIdentity();
-    }
+    from_c_matrix(cmatrix, &matrix);
     SkShader* s = SkGradientShader::CreateLinear(reinterpret_cast<const SkPoint*>(pts),
                                                  reinterpret_cast<const SkColor*>(colors),
                                                  colorPos, colorCount, mode, 0, &matrix);
     return (sk_shader_t*)s;
 }
 
 ///////////////////////////////////////////////////////////////////////////////////////////
 ///////////////////////////////////////////////////////////////////////////////////////////
 
 void sk_test_capi(SkCanvas* canvas) {
@@ skipping 31 matching lines @@
     sk_image_t* cimage = sk_surface_new_image_snapshot(csurface);
     
     // HERE WE CROSS THE C..C++ boundary
     canvas->drawImage((const SkImage*)cimage, 20, 20, NULL);
     
     sk_path_delete(cpath);
     sk_paint_delete(cpaint);
     sk_image_unref(cimage);
     sk_surface_unref(csurface);
 }