[PATCH 4/4] d2d1: Implement D2D1MakeSkewMatrix().

[Nikolay Sivov]

Signed-off-by: Nikolay Sivov <nsivov at codeweavers.com>
---
 dlls/d2d1/d2d1.spec    |  2 +-
 dlls/d2d1/factory.c    | 18 ++++++++++++++++++
 dlls/d2d1/tests/d2d1.c | 39 +++++++++++++++++++++++++++++++++++++++
 include/d2d1.idl       |  1 +
 4 files changed, 59 insertions(+), 1 deletion(-)

diff --git a/dlls/d2d1/d2d1.spec b/dlls/d2d1/d2d1.spec
index 3443b29505..fff6f1c9c8 100644
--- a/dlls/d2d1/d2d1.spec
+++ b/dlls/d2d1/d2d1.spec
@@ -1,6 +1,6 @@
 @ stdcall D2D1CreateFactory(long ptr ptr ptr)
 @ stdcall D2D1MakeRotateMatrix(float float float ptr)
-@ stub D2D1MakeSkewMatrix
+@ stdcall D2D1MakeSkewMatrix(float float float float ptr)
 @ stdcall D2D1IsMatrixInvertible(ptr)
 @ stdcall D2D1InvertMatrix(ptr)
 @ stub D2D1ConvertColorSpace
diff --git a/dlls/d2d1/factory.c b/dlls/d2d1/factory.c
index 2459b58c03..8d9d8c324b 100644
--- a/dlls/d2d1/factory.c
+++ b/dlls/d2d1/factory.c
@@ -592,6 +592,24 @@ void WINAPI D2D1MakeRotateMatrix(float angle, D2D1_POINT_2F center, D2D1_MATRIX_
     matrix->_32 = center.y - center.x * sin_theta - center.y * cos_theta;
 }
 
+void WINAPI D2D1MakeSkewMatrix(float angle_x, float angle_y, D2D1_POINT_2F center, D2D1_MATRIX_3X2_F *matrix)
+{
+    float tan_x, tan_y;
+
+    TRACE("angle_x %.8e, angle_y %.8e, center %s, matrix %p.\n", angle_x, angle_y, debug_d2d_point_2f(&center), matrix);
+
+    tan_x = tan(angle_x * (M_PI / 180.0f));
+    tan_y = tan(angle_y * (M_PI / 180.0f));
+
+    /* translate(-center) * skew() * translate(center) */
+    matrix->_11 = 1.0f;
+    matrix->_12 = tan_y;
+    matrix->_21 = tan_x;
+    matrix->_22 = 1.0f;
+    matrix->_31 = -tan_x * center.y;
+    matrix->_32 = -tan_y * center.x;
+}
+
 BOOL WINAPI D2D1IsMatrixInvertible(const D2D1_MATRIX_3X2_F *matrix)
 {
     TRACE("matrix %p.\n", matrix);
diff --git a/dlls/d2d1/tests/d2d1.c b/dlls/d2d1/tests/d2d1.c
index d00fba1b41..0bea1c80a8 100644
--- a/dlls/d2d1/tests/d2d1.c
+++ b/dlls/d2d1/tests/d2d1.c
@@ -7601,6 +7601,44 @@ static void test_invert_matrix(void)
     }
 }
 
+static void test_skew_matrix(void)
+{
+    static const struct
+    {
+        float angle_x;
+        float angle_y;
+        D2D1_POINT_2F center;
+        D2D1_MATRIX_3X2_F matrix;
+    }
+    skew_tests[] =
+    {
+        { 0.0f, 0.0f, { 0.0f, 0.0f }, { 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f } },
+        { 45.0f, 0.0f, { 0.0f, 0.0f }, { 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f } },
+        { 0.0f, 0.0f, { 10.0f, -3.0f }, { 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f } },
+        { -45.0f, 45.0f, { 0.1f, 0.5f }, { 1.0f, 1.0f, -1.0f, 1.0f, 0.5f, -0.1f } },
+        { -45.0f, 45.0f, { 1.0f, 2.0f }, { 1.0f, 1.0f, -1.0f, 1.0f, 2.0f, -1.0f } },
+        { 45.0f, -45.0f, { 1.0f, 2.0f }, { 1.0f, -1.0f, 1.0f, 1.0f, -2.0f, 1.0f } },
+        { 30.0f, -60.0f, { 12.0f, -5.0f }, { 1.0f, -1.7320509f, 0.577350259f, 1.0f, 2.88675117f, 20.7846107f } },
+    };
+    unsigned int i;
+
+    for (i = 0; i < ARRAY_SIZE(skew_tests); ++i)
+    {
+        const D2D1_MATRIX_3X2_F *expected = &skew_tests[i].matrix;
+        D2D1_MATRIX_3X2_F m;
+        BOOL ret;
+
+        D2D1MakeSkewMatrix(skew_tests[i].angle_x, skew_tests[i].angle_y, skew_tests[i].center, &m);
+        ret = compare_float(m._11, expected->_11, 3) && compare_float(m._12, expected->_12, 3)
+                && compare_float(m._21, expected->_21, 3) && compare_float(m._22, expected->_22, 3)
+                && compare_float(m._31, expected->_31, 3) && compare_float(m._32, expected->_32, 3);
+
+        ok(ret, "%u: unexpected matrix value {%.8e, %.8e, %.8e, %.8e, %.8e, %.8e}, expected "
+                "{%.8e, %.8e, %.8e, %.8e, %.8e, %.8e}.\n", i, m._11, m._12, m._21, m._22, m._31, m._32,
+                expected->_11, expected->_12, expected->_21, expected->_22, expected->_31, expected->_32);
+    }
+}
+
 START_TEST(d2d1)
 {
     unsigned int argc, i;
@@ -7643,6 +7681,7 @@ START_TEST(d2d1)
     queue_test(test_bitmap_surface);
     queue_test(test_device_context);
     queue_test(test_invert_matrix);
+    queue_test(test_skew_matrix);
 
     run_queued_tests();
 }
diff --git a/include/d2d1.idl b/include/d2d1.idl
index ff2dc03cfd..c9fb8f0b6b 100644
--- a/include/d2d1.idl
+++ b/include/d2d1.idl
@@ -1257,3 +1257,4 @@ interface ID2D1Factory : IUnknown
 [local] BOOL __stdcall D2D1InvertMatrix(D2D1_MATRIX_3X2_F *matrix);
 [local] BOOL __stdcall D2D1IsMatrixInvertible(const D2D1_MATRIX_3X2_F *matrix);
 [local] void __stdcall D2D1MakeRotateMatrix(float angle, D2D1_POINT_2F center, D2D1_MATRIX_3X2_F *matrix);
+[local] void __stdcall D2D1MakeSkewMatrix(float angle_x, float angle_y, D2D1_POINT_2F center, D2D1_MATRIX_3X2_F *matrix);
-- 
2.19.0