[C/C++]解决使用VS图形库putimage渲染png图片出现黑边情况

梦里梦外; 2024-04-24 20:33 18阅读 0赞

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> 在使用VS图形库时候,可能使用putimage函数渲染的png格式的图片透明部分会变成黑边,则使用该putimagePNG接口可以去掉黑边,使黑色部分呈现透明状态 ,代码如下:

//头文件
    #pragma once
    #include <graphics.h>
    
    void putimagePNG(int  picture_x, int picture_y, IMAGE* picture);
    int getDelay();

#include "tools.h"
    
    // 载入PNG图并去透明部分
    void _putimagePNG(int  picture_x, int picture_y, IMAGE* picture) //x为载入图片的X坐标，y为Y坐标
    {
    	DWORD* dst = GetImageBuffer();    // GetImageBuffer()函数，用于获取绘图设备的显存指针，EASYX自带
    	DWORD* draw = GetImageBuffer();
    	DWORD* src = GetImageBuffer(picture); //获取picture的显存指针
    	int picture_width = picture->getwidth(); //获取picture的宽度，EASYX自带
    	int picture_height = picture->getheight(); //获取picture的高度，EASYX自带
    	int graphWidth = getwidth();       //获取绘图区的宽度，EASYX自带
    	int graphHeight = getheight();     //获取绘图区的高度，EASYX自带
    	int dstX = 0;    //在显存里像素的角标
    
    	// 实现透明贴图 公式： Cp=αp*FP+(1-αp)*BP ， 贝叶斯定理来进行点颜色的概率计算
    	for (int iy = 0; iy < picture_height; iy++)
    	{
    		for (int ix = 0; ix < picture_width; ix++)
    		{
    			int srcX = ix + iy * picture_width; //在显存里像素的角标
    			int sa = ((src[srcX] & 0xff000000) >> 24); //0xAArrggbb;AA是透明度
    			int sr = ((src[srcX] & 0xff0000) >> 16); //获取RGB里的R
    			int sg = ((src[srcX] & 0xff00) >> 8);   //G
    			int sb = src[srcX] & 0xff;              //B
    			if (ix >= 0 && ix <= graphWidth && iy >= 0 && iy <= graphHeight && dstX <= graphWidth * graphHeight)
    			{
    				dstX = (ix + picture_x) + (iy + picture_y) * graphWidth; //在显存里像素的角标
    				int dr = ((dst[dstX] & 0xff0000) >> 16);
    				int dg = ((dst[dstX] & 0xff00) >> 8);
    				int db = dst[dstX] & 0xff;
    				draw[dstX] = ((sr * sa / 255 + dr * (255 - sa) / 255) << 16)
    					| ((sg * sa / 255 + dg * (255 - sa) / 255) << 8)
    					| (sb * sa / 255 + db * (255 - sa) / 255);
    			}
    		}
    	}
    }
    
    // 适用于 y <0 以及x<0的任何情况
    void putimagePNG(int x, int y, IMAGE* picture) {
    
    	IMAGE imgTmp, imgTmp2, imgTmp3;
    	int winWidth = getwidth();
    	int winHeight = getheight();
    	if (y < 0) {
    		SetWorkingImage(picture);
    		getimage(&imgTmp, 0, -y,
    			picture->getwidth(), picture->getheight() + y);
    		SetWorkingImage();
    		y = 0;
    		picture = &imgTmp;
    	}
    	else if (y >= getheight() || x >= getwidth()) {
    		return;
    	}
    	else if (y + picture->getheight() > winHeight) {
    		SetWorkingImage(picture);
    		getimage(&imgTmp, x, y, picture->getwidth(), winHeight - y);
    		SetWorkingImage();
    		picture = &imgTmp;
    	}
    
    	if (x < 0) {
    		SetWorkingImage(picture);
    		getimage(&imgTmp2, -x, 0, picture->getwidth() + x, picture->getheight());
    		SetWorkingImage();
    		x = 0;
    		picture = &imgTmp2;
    	}
    
    	if (x > winWidth - picture->getwidth()) {
    		SetWorkingImage(picture);
    		getimage(&imgTmp3, 0, 0, winWidth - x, picture->getheight());
    		SetWorkingImage();
    		picture = &imgTmp3;
    	}
    
    
    	_putimagePNG(x, y, picture);
    }
    
    int getDelay() {
    	static unsigned long long lastTime = 0;
    	unsigned long long currentTime = GetTickCount();
    	if (lastTime == 0) {
    		lastTime = currentTime;
    		return 0;
    	}
    	else {
    		int ret = currentTime - lastTime;
    		lastTime = currentTime;
    		return ret;
    	}
    }

[Link 1]: https://blog.csdn.net/weixin_73865721?spm=1010.2135.3001.5343
[C_C]: https://blog.csdn.net/weixin_73865721?type=blog