Merge pull request #33 from chirsz-ever/putpixel-withalpha-2007

增加 `ege::putpixel_withalpha` 与 `ege::putpixel_withalpha_f`

src/color.cpp

@@ -321,4 +321,13 @@ hsv2rgb(float H, float S, float V) {
 	return EGERGB(crgb.r, crgb.g, crgb.b);
 }
 
+color_t alphablend(color_t dst, color_t src) {
+	return alphablend_inline(dst, src, EGEGET_A(src));
+}
+
+color_t alphablend(color_t dst, color_t src, unsigned char alpha) {
+	return alphablend_inline(dst, src, alpha);
+}
+
+
 } // namespace ege

src/ege.h

@@ -467,7 +467,7 @@ typedef enum pattern_type_e {
 	pattern_texture         = 3,
 }pattern_type_e;
 
-typedef unsigned int color_t;
+typedef DWORD color_t;
 
 struct viewporttype {
 	int left;
@@ -705,16 +705,23 @@ void        EGEAPI rgb2hsv(color_t rgb, float *H, float *S, float *V);
 color_t     EGEAPI hsl2rgb(float H, float S, float L);
 color_t     EGEAPI hsv2rgb(float H, float S, float V);
 
+// 按 Alpha 通道混合颜色，将 src 作为背景色，dst 作为前景色进行混合
+color_t     EGEAPI alphablend(color_t dst, color_t src); // 使用 EGEGET_A(src) 作为 Alpha 值
+color_t     EGEAPI alphablend(color_t dst, color_t src, unsigned char alpha);
+
 
 // 基本绘图函数
 
 color_t     EGEAPI getpixel  (int x, int y, PCIMAGE pimg = NULL);               // 获取点的颜色
 void        EGEAPI putpixel  (int x, int y, color_t color, PIMAGE pimg = NULL); // 画点
 color_t     EGEAPI getpixel_f(int x, int y, PCIMAGE pimg = NULL);               // 获取点的颜色
-void        EGEAPI putpixel_f(int x, int y, color_t color, PIMAGE pimg = NULL); // 画点
+void        EGEAPI putpixel_f(int x, int y, color_t color, PIMAGE pimg = NULL); // 绝对坐标画点
 void        EGEAPI putpixels  (int nPoint, int* pPoints, PIMAGE pimg = NULL);   // 批量画点
 void        EGEAPI putpixels_f(int nPoint, int* pPoints, PIMAGE pimg = NULL);   // 批量画点
 
+void        EGEAPI putpixel_withalpha  (int x, int y, color_t color, PIMAGE pimg = NULL); // 带透明度画点
+void        EGEAPI putpixel_withalpha_f(int x, int y, color_t color, PIMAGE pimg = NULL); // 带透明度绝对坐标画点
+
 void EGEAPI moveto(int x, int y, PIMAGE pimg = NULL);                      // 移动当前点(绝对坐标)
 void EGEAPI moverel(int dx, int dy, PIMAGE pimg = NULL);                   // 移动当前点(相对坐标)
 

src/ege_head.h

@@ -103,6 +103,12 @@
 #endif
 #endif
 
+#ifdef _MSC_VER
+#define EGE_FORCEINLINE   __forceinline
+#else
+#define EGE_FORCEINLINE   __attribute__((always_inline)) inline
+#endif
+
 #define EGE_GDIPLUS // 使用gdi+函数扩展
 
 #ifdef EGE_GDIPLUS
@@ -566,6 +572,17 @@ void internal_panic(LPCWSTR errmsg);
 
 HBITMAP newbitmap(int width, int height, PDWORD* p_bmp_buf);
 
+// 以 bkg 为背景色，src 为前景色，alpha 为 0~255 的整数进行混合，
+// 混合结果保留 bkg 的 Alpha 通道
+EGE_FORCEINLINE color_t alphablend_inline(color_t bkg, color_t src, unsigned char alpha) {
+	DWORD rb = bkg & 0x00FF00FF;
+	DWORD  g = bkg & 0x0000FF00;
+
+	rb += ((src & 0x00FF00FF) - rb) * alpha >> 8;
+	g  += ((src & 0x0000FF00) -  g) * alpha >> 8;
+	return (rb & 0x00FF00FF) | (g & 0x0000FF00) | (bkg & 0xFF000000);
+}
+
 } // namespace ege
 
 #endif /*_EGE_HEAD_H_*/

src/egegapi.cpp

@@ -451,6 +451,26 @@ putpixel_f(int x, int y, color_t color, PIMAGE pimg) {
 	}
 }
 
+void putpixel_withalpha(int x, int y, color_t color, PIMAGE pimg) {
+	PIMAGE img = CONVERT_IMAGE(pimg);
+	x += img->m_vpt.left;
+	y += img->m_vpt.top;
+	if (in_rect(x, y, img->m_vpt.right, img->m_vpt.bottom)) {
+		color_t& dst_color = img->m_pBuffer[y * img->m_width + x];
+		dst_color = alphablend_inline(dst_color, color, EGEGET_A(color));
+	}
+	CONVERT_IMAGE_END;
+}
+
+void putpixel_withalpha_f(int x, int y, color_t color, PIMAGE pimg) {
+	PIMAGE img = CONVERT_IMAGE_F(pimg);
+	if (in_rect(x, y, img->m_width, img->m_height)) {
+		color_t& dst_color = img->m_pBuffer[y * img->m_width + x];
+		dst_color = alphablend_inline(dst_color, color, EGEGET_A(color));
+	}
+	CONVERT_IMAGE_END;
+}
+
 void
 moveto(int x, int y, PIMAGE pimg) {
 	PIMAGE img = CONVERT_IMAGE(pimg);

src/image.cpp

@@ -859,15 +859,6 @@ IMAGE::putimage_transparent(
 	return grOk;
 }
 
-#define EGEALPHABLEND(d, s, pd, alpha) do {                            \
-		DWORD rb = d & 0x00FF00FF;                                     \
-		DWORD  g = d & 0x0000FF00;                                     \
-                                                                       \
-		rb += ((s & 0x00FF00FF) - rb) * alpha >> 8;                    \
-		g  += ((s & 0x0000FF00) -  g) * alpha >> 8;                    \
-		*pd = (rb & 0x00FF00FF) | (g & 0x0000FF00) | (d & 0xFF000000); \
-	} while(0)
-
 int
 IMAGE::putimage_alphablend(
 	PIMAGE imgdest,         // handle to dest
@@ -905,7 +896,7 @@ IMAGE::putimage_alphablend(
 		for (y=0; y<nHeightSrc; ++y) {
 			for (x=0; x<nWidthSrc; ++x, ++psp, ++pdp) {
 				DWORD d=*pdp, s=*psp;
-				EGEALPHABLEND(d, s, pdp, alpha);
+				*pdp = alphablend_inline(d, s, alpha);
 			}
 			pdp += ddx;
 			psp += dsx;
@@ -955,7 +946,7 @@ IMAGE::putimage_alphatransparent(
 			for (x=0; x<nWidthSrc; ++x, ++psp, ++pdp) {
 				if ((*psp & 0x00FFFFFF) != cr) {
 					DWORD d=*pdp, s=*psp;
-					EGEALPHABLEND(d, s, pdp, alpha);
+					*pdp = alphablend_inline(d, s, alpha);
 				}
 			}
 			pdp += ddx;
@@ -1003,7 +994,7 @@ IMAGE::putimage_withalpha(
 			for (x=0; x<nWidthSrc; ++x, ++psp, ++pdp) {
 				DWORD d=*pdp, s=*psp;
 				DWORD alpha = EGEGET_A(s);
-				EGEALPHABLEND(d, s, pdp, alpha);
+				*pdp = alphablend_inline(d, s, alpha);
 			}
 			pdp += ddx;
 			psp += dsx;
@@ -1054,7 +1045,7 @@ IMAGE::putimage_alphafilter(
 				DWORD d=*pdp, s=*psp;
 				DWORD alpha = *pap & 0xFF;
 				if (*pap) {
-					EGEALPHABLEND(d, s, pdp, alpha);
+					*pdp = alphablend_inline(d, s, alpha);
 				}
 			}
 			pdp += ddx;