Milestone 5: deliver embedded RDP sessions and lifecycle hardening

third_party/FreeRDP/libfreerdp/primitives/prim_alphaComp.c

@@ -0,0 +1,98 @@
+/* FreeRDP: A Remote Desktop Protocol Client
+ * Alpha blending routines.
+ * vi:ts=4 sw=4:
+ *
+ * (c) Copyright 2012 Hewlett-Packard Development Company, L.P.
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License. You may obtain
+ * a copy of the License at http://www.apache.org/licenses/LICENSE-2.0.
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ *
+ * Note: this code assumes the second operand is fully opaque,
+ * e.g.
+ *   newval = alpha1*val1 + (1-alpha1)*val2
+ * rather than
+ *   newval = alpha1*val1 + (1-alpha1)*alpha2*val2
+ */
+
+#include <freerdp/config.h>
+
+#include <freerdp/types.h>
+#include <freerdp/primitives.h>
+
+#include "prim_internal.h"
+#include "prim_alphaComp.h"
+
+#define ALPHA(_k_) (((_k_)&0xFF000000U) >> 24)
+
+/* ------------------------------------------------------------------------- */
+static pstatus_t general_alphaComp_argb(const BYTE* WINPR_RESTRICT pSrc1, UINT32 src1Step,
+                                        const BYTE* WINPR_RESTRICT pSrc2, UINT32 src2Step,
+                                        BYTE* WINPR_RESTRICT pDst, UINT32 dstStep, UINT32 width,
+                                        UINT32 height)
+{
+	for (size_t y = 0; y < height; y++)
+	{
+		const UINT32* sptr1 = (const UINT32*)(pSrc1 + y * src1Step);
+		const UINT32* sptr2 = (const UINT32*)(pSrc2 + y * src2Step);
+		UINT32* dptr = (UINT32*)(pDst + y * dstStep);
+
+		for (size_t x = 0; x < width; x++)
+		{
+			const UINT32 src1 = *sptr1++;
+			const UINT32 src2 = *sptr2++;
+			UINT32 alpha = ALPHA(src1) + 1;
+
+			if (alpha == 256)
+			{
+				/* If alpha is 255+1, just copy src1. */
+				*dptr++ = src1;
+			}
+			else if (alpha <= 1)
+			{
+				/* If alpha is 0+1, just copy src2. */
+				*dptr++ = src2;
+			}
+			else
+			{
+				/* A perfectly accurate blend would do (a*src + (255-a)*dst)/255
+				 * rather than adding one to alpha and dividing by 256, but this
+				 * is much faster and only differs by one 16% of the time.
+				 * I'm not sure who first designed the double-ops trick
+				 * (Red Blue and Alpha Green).
+				 */
+				UINT32 rb = 0;
+				UINT32 ag = 0;
+				UINT32 s2rb = src2 & 0x00FF00FFU;
+				UINT32 s2ag = (src2 >> 8) & 0x00FF00FFU;
+				UINT32 s1rb = src1 & 0x00FF00FFU;
+				UINT32 s1ag = (src1 >> 8) & 0x00FF00FFU;
+				UINT32 drb = s1rb - s2rb;
+				UINT32 dag = s1ag - s2ag;
+				drb *= alpha;
+				dag *= alpha;
+				rb = ((drb >> 8) + s2rb) & 0x00FF00FFU;
+				ag = (((dag >> 8) + s2ag) << 8) & 0xFF00FF00U;
+				*dptr++ = rb | ag;
+			}
+		}
+	}
+
+	return PRIMITIVES_SUCCESS;
+}
+
+/* ------------------------------------------------------------------------- */
+void primitives_init_alphaComp(primitives_t* WINPR_RESTRICT prims)
+{
+	prims->alphaComp_argb = general_alphaComp_argb;
+}
+
+void primitives_init_alphaComp_opt(primitives_t* WINPR_RESTRICT prims)
+{
+	primitives_init_alphaComp(prims);
+	primitives_init_alphaComp_sse3(prims);
+}