C API: add radial, sweep, and two-point conical gradient shaders

Review URL: https://codereview.chromium.org/1263773006

3 files changed, 230 insertions, 1 deletions

diff --git a/include/c/sk_shader.h b/include/c/sk_shader.h
index 9f83ff0415..702cda7fd4 100644
--- a/include/c/sk_shader.h
+++ b/include/c/sk_shader.h
@@ -24,13 +24,119 @@ typedef enum {
     MIRROR_SK_SHADER_TILEMODE,
 } sk_shader_tilemode_t;
 
-sk_shader_t* sk_shader_new_linear_gradient(const sk_point_t pts[2],
+/**
+    Returns a shader that generates a linear gradient between the two
+    specified points.
+
+    @param points The start and end points for the gradient.
+    @param colors The array[count] of colors, to be distributed between
+                  the two points
+    @param colorPos May be NULL. array[count] of SkScalars, or NULL, of
+                    the relative position of each corresponding color
+                    in the colors array. If this is NULL, the the
+                    colors are distributed evenly between the start
+                    and end point.  If this is not null, the values
+                    must begin with 0, end with 1.0, and intermediate
+                    values must be strictly increasing.
+    @param colorCount Must be >=2. The number of colors (and pos if not
+                      NULL) entries.
+    @param mode The tiling mode
+*/
+sk_shader_t* sk_shader_new_linear_gradient(const sk_point_t points[2],
+                                           const sk_color_t colors[],
+                                           const float colorPos[],
+                                           int colorCount,
+                                           sk_shader_tilemode_t tileMode,
+                                           const sk_matrix_t* localMatrix);
+
+
+/**
+    Returns a shader that generates a radial gradient given the center
+    and radius.
+
+    @param center The center of the circle for this gradient
+    @param radius Must be positive. The radius of the circle for this
+                  gradient
+    @param colors The array[count] of colors, to be distributed
+                  between the center and edge of the circle
+    @param colorPos May be NULL. The array[count] of the relative
+                    position of each corresponding color in the colors
+                    array. If this is NULL, the the colors are
+                    distributed evenly between the center and edge of
+                    the circle.  If this is not null, the values must
+                    begin with 0, end with 1.0, and intermediate
+                    values must be strictly increasing.
+    @param count Must be >= 2. The number of colors (and pos if not
+                 NULL) entries
+    @param tileMode The tiling mode
+    @param localMatrix May be NULL
+*/
+sk_shader_t* sk_shader_new_radial_gradient(const sk_point_t* center,
+                                           float radius,
                                            const sk_color_t colors[],
                                            const float colorPos[],
                                            int colorCount,
                                            sk_shader_tilemode_t tileMode,
                                            const sk_matrix_t* localMatrix);
 
+/**
+    Returns a shader that generates a sweep gradient given a center.
+
+    @param center The coordinates of the center of the sweep
+    @param colors The array[count] of colors, to be distributed around
+                  the center.
+    @param colorPos May be NULL. The array[count] of the relative
+                    position of each corresponding color in the colors
+                    array. If this is NULL, the the colors are
+                    distributed evenly between the center and edge of
+                    the circle.  If this is not null, the values must
+                    begin with 0, end with 1.0, and intermediate
+                    values must be strictly increasing.
+    @param colorCount Must be >= 2. The number of colors (and pos if
+                      not NULL) entries
+    @param localMatrix May be NULL
+*/
+sk_shader_t* sk_shader_new_sweep_gradient(const sk_point_t* center,
+                                          const sk_color_t colors[],
+                                          const float colorPos[],
+                                          int colorCount,
+                                          const sk_matrix_t* localMatrix);
+
+/**
+    Returns a shader that generates a conical gradient given two circles, or
+    returns NULL if the inputs are invalid. The gradient interprets the
+    two circles according to the following HTML spec.
+    http://dev.w3.org/html5/2dcontext/#dom-context-2d-createradialgradient
+
+    Returns a shader that generates a sweep gradient given a center.
+
+    @param start, startRadius Defines the first circle.
+    @param end, endRadius Defines the first circle.
+    @param colors The array[count] of colors, to be distributed between
+                  the two circles.
+    @param colorPos May be NULL. The array[count] of the relative
+                    position of each corresponding color in the colors
+                    array. If this is NULL, the the colors are
+                    distributed evenly between the two circles.  If
+                    this is not null, the values must begin with 0,
+                    end with 1.0, and intermediate values must be
+                    strictly increasing.
+    @param colorCount Must be >= 2. The number of colors (and pos if
+                      not NULL) entries
+    @param tileMode The tiling mode
+    @param localMatrix May be NULL
+
+*/
+sk_shader_t* sk_shader_new_two_point_conical_gradient(
+        const sk_point_t* start,
+        float startRadius,
+        const sk_point_t* end,
+        float endRadius,
+        const sk_color_t colors[],
+        const float colorPos[],
+        int colorCount,
+        sk_shader_tilemode_t tileMode,
+        const sk_matrix_t* localMatrix);
 
 SK_C_PLUS_PLUS_END_GUARD
 
diff --git a/src/c/sk_surface.cpp b/src/c/sk_surface.cpp
index 84a9c541c2..ccab9dfa1a 100644
--- a/src/c/sk_surface.cpp
+++ b/src/c/sk_surface.cpp
@@ -556,6 +556,86 @@ sk_shader_t* sk_shader_new_linear_gradient(const sk_point_t pts[2],
     return (sk_shader_t*)s;
 }
 
+static const SkPoint& to_skpoint(const sk_point_t& p) {
+    return reinterpret_cast<const SkPoint&>(p);
+}
+
+sk_shader_t* sk_shader_new_radial_gradient(const sk_point_t* ccenter,
+                                           float radius,
+                                           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) {
+        from_c_matrix(cmatrix, &matrix);
+    } else {
+        matrix.setIdentity();
+    }
+    SkPoint center = to_skpoint(*ccenter);
+    SkShader* s = SkGradientShader::CreateRadial(
+            center, (SkScalar)radius,
+            reinterpret_cast<const SkColor*>(colors),
+            reinterpret_cast<const SkScalar*>(colorPos),
+            colorCount, mode, 0, &matrix);
+    return (sk_shader_t*)s;
+}
+
+sk_shader_t* sk_shader_new_sweep_gradient(const sk_point_t* ccenter,
+                                          const sk_color_t colors[],
+                                          const float colorPos[],
+                                          int colorCount,
+                                          const sk_matrix_t* cmatrix) {
+    SkMatrix matrix;
+    if (cmatrix) {
+        from_c_matrix(cmatrix, &matrix);
+    } else {
+        matrix.setIdentity();
+    }
+    SkShader* s = SkGradientShader::CreateSweep(
+            (SkScalar)(ccenter->x),
+            (SkScalar)(ccenter->y),
+            reinterpret_cast<const SkColor*>(colors),
+            reinterpret_cast<const SkScalar*>(colorPos),
+            colorCount, 0, &matrix);
+    return (sk_shader_t*)s;
+}
+
+sk_shader_t* sk_shader_new_two_point_conical_gradient(const sk_point_t* start,
+                                                      float startRadius,
+                                                      const sk_point_t* end,
+                                                      float endRadius,
+                                                      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) {
+        from_c_matrix(cmatrix, &matrix);
+    } else {
+        matrix.setIdentity();
+    }
+    SkPoint skstart = to_skpoint(*start);
+    SkPoint skend = to_skpoint(*end);
+    SkShader* s = SkGradientShader::CreateTwoPointConical(
+            skstart, (SkScalar)startRadius,
+            skend, (SkScalar)endRadius,
+            reinterpret_cast<const SkColor*>(colors),
+            reinterpret_cast<const SkScalar*>(colorPos),
+            colorCount, mode, 0, &matrix);
+    return (sk_shader_t*)s;
+}
+
 ///////////////////////////////////////////////////////////////////////////////////////////
 
 #include "../../include/effects/SkBlurMaskFilter.h"
diff --git a/tests/CTest.cpp b/tests/CTest.cpp
index acab4bb11b..4cc8cd6666 100644
--- a/tests/CTest.cpp
+++ b/tests/CTest.cpp
@@ -8,9 +8,51 @@
 #include "sk_canvas.h"
 #include "sk_paint.h"
 #include "sk_surface.h"
+#include "sk_shader.h"
 
 #include "Test.h"
 
+
+static void shader_test(skiatest::Reporter* reporter) {
+    sk_imageinfo_t info =
+        {64, 64, sk_colortype_get_default_8888(), PREMUL_SK_ALPHATYPE};
+    sk_surface_t* surface  = sk_surface_new_raster(&info, NULL);
+    sk_canvas_t* canvas = sk_surface_get_canvas(surface);
+    sk_paint_t* paint = sk_paint_new();
+
+    sk_shader_tilemode_t tilemode = CLAMP_SK_SHADER_TILEMODE;
+    sk_point_t point = {0.0f, 0.0f};
+    sk_point_t point2 = {30.0f, 40.0f};
+    sk_color_t colors[] = {
+        (sk_color_t)sk_color_set_argb(0xFF, 0x00, 0x00, 0xFF),
+        (sk_color_t)sk_color_set_argb(0xFF, 0x00, 0xFF, 0x00)
+    };
+    sk_shader_t* shader;
+
+    shader = sk_shader_new_radial_gradient(
+            &point, 1.0f, colors, NULL, 2, tilemode, NULL);
+    REPORTER_ASSERT(reporter, shader != NULL);
+    sk_paint_set_shader(paint, shader);
+    sk_shader_unref(shader);
+    sk_canvas_draw_paint(canvas, paint);
+
+    shader = sk_shader_new_sweep_gradient(&point, colors, NULL, 2, NULL);
+    REPORTER_ASSERT(reporter, shader != NULL);
+    sk_paint_set_shader(paint, shader);
+    sk_shader_unref(shader);
+    sk_canvas_draw_paint(canvas, paint);
+
+    shader = sk_shader_new_two_point_conical_gradient(
+            &point, 10.0f,  &point2, 50.0f, colors, NULL, 2, tilemode, NULL);
+    REPORTER_ASSERT(reporter, shader != NULL);
+    sk_paint_set_shader(paint, shader);
+    sk_shader_unref(shader);
+    sk_canvas_draw_paint(canvas, paint);
+
+    sk_paint_delete(paint);
+    sk_surface_unref(surface);
+}
+
 static void test_c(skiatest::Reporter* reporter) {
     sk_colortype_t ct = sk_colortype_get_default_8888();
 
@@ -43,4 +85,5 @@ static void test_c(skiatest::Reporter* reporter) {
 
 DEF_TEST(C_API, reporter) {
     test_c(reporter);
+    shader_test(reporter);
 }