颜色 渐变矩形

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//绘制颜色渐变区域的函数: DrawGradientV(垂直渐变) DrawGradientH(水平渐变)

//设置渐变参数，GRADLEVEL越小，颜色渐变越细腻，过度效果越好，但速度比较慢

#define GRADLEVEL 2    

/****************************************************************************

绘制垂直颜色渐变区域

DrawGradientV(    HDC hdc            //绘图刷子

COLORREF co1    //顶端颜色

COLORREF co2    //低端颜色

RECT& DrawRect)    //颜色渐变区域

****************************************************************************/

void DrawGradientV( HDC hdc, COLORREF co1, COLORREF co2, RECT& DrawRect )

{

int r = GetRValue( co1 );

int g = GetGValue( co1 );

int b = GetBValue( co1 );

int r2 = GetRValue( co2 );

int g2 = GetGValue( co2 );

int b2 = GetBValue( co2 );

//计算宽,高

int DrawRectWidth=DrawRect.right-DrawRect.left;

int DrawRectHeight=DrawRect.bottom-DrawRect.top;

if ( DrawRectWidth<=0)

return;

//初始化rect

RECT rect={0,0,DrawRectWidth,GRADLEVEL};

//准备GDI

HDC hMemDC=CreateCompatibleDC(hdc);                //创建内存DC

HBITMAP hBitmap=::CreateCompatibleBitmap(hdc,DrawRectWidth,DrawRectHeight);//创建位图

::SelectObject(hMemDC,hBitmap);        //把位图选进内存DC

HBRUSH hbr;

for(int i = DrawRectHeight; i > 0; i -= GRADLEVEL ) 

{

//创建刷子

hbr = CreateSolidBrush( RGB( r, g, b ) );

FillRect( hMemDC, &rect, hbr );

DeleteObject( hbr );

//改变小正方体的位置

rect.top += GRADLEVEL;

rect.bottom += GRADLEVEL;

//判断小正方体是否超界

if( rect.bottom > DrawRect.bottom )

rect.bottom = DrawRect.bottom;

//改变颜色

r += ( r2 - r + i / 2 ) / i * GRADLEVEL;

g += ( g2 - g + i / 2 ) / i * GRADLEVEL;

b += ( b2 - b + i / 2 ) / i * GRADLEVEL;

}

//内存DC映射到屏幕DC

BitBlt(hdc,DrawRect.left,DrawRect.top,DrawRectWidth,DrawRectHeight,hMemDC,0,0,SRCCOPY);    

//删除

::DeleteDC(hMemDC) ;                        

::DeleteObject(hBitmap);    

}

/****************************************************************************

绘制水平颜色渐变区域

DrawGradientV(    HDC hdc            //绘图刷子

COLORREF co1    //左端颜色

COLORREF co2    //右端颜色

RECT& DrawRect)    //颜色渐变区域

****************************************************************************/

void DrawGradientH( HDC hdc, COLORREF co1, COLORREF co2, RECT& DrawRect )

{

int r = GetRValue( co1 );

int g = GetGValue( co1 );

int b = GetBValue( co1 );

int r2 = GetRValue( co2 );

int g2 = GetGValue( co2 );

int b2 = GetBValue( co2 );

//计算宽,高

int DrawRectWidth=DrawRect.right-DrawRect.left;

int DrawRectHeight=DrawRect.bottom-DrawRect.top;

if ( DrawRectHeight<=0)

return;

//初始化rect

RECT rect={0,0,GRADLEVEL,DrawRectHeight};

//准备GDI

HDC hMemDC=CreateCompatibleDC(hdc);                //创建内存DC

HBITMAP hBitmap=::CreateCompatibleBitmap(hdc,DrawRectWidth,DrawRectHeight);//创建位图

::SelectObject(hMemDC,hBitmap);        //把位图选进内存DC

HBRUSH hbr;

for(int i = DrawRectWidth; i > 0; i -= GRADLEVEL ) 

{

//创建刷子

hbr = CreateSolidBrush( RGB( r, g, b ) );

FillRect( hMemDC, &rect, hbr );

DeleteObject( hbr );

//改变小正方体的位置

rect.left += GRADLEVEL;

rect.right += GRADLEVEL;

//判断小正方体是否超界

if( rect.right > DrawRect.right )

rect.right = DrawRect.right;

//改变颜色

r += ( r2 - r + i / 2 ) / i * GRADLEVEL;

g += ( g2 - g + i / 2 ) / i * GRADLEVEL;

b += ( b2 - b + i / 2 ) / i * GRADLEVEL;

TRACE("i:%d  r=%d,g=%d,b=%d\n",i,r,g,b);

}

//内存DC映射到屏幕DC

BitBlt(hdc,DrawRect.left,DrawRect.top,DrawRectWidth,DrawRectHeight,hMemDC,0,0,SRCCOPY);    

//删除

::DeleteDC(hMemDC) ;                        

::DeleteObject(hBitmap);    

}

void DrawShadeRect(CDC* pdc, CRect crect, COLORREF top, COLORREF bottom )

{

CRect stepR;     

COLORREF color;   

float fStep;

fStep = ((float)crect.Height())/255.0f;

CRect rect(crect);

for (int iOnBand = 0; iOnBand < 255; iOnBand++) 

{

if ( (int)(iOnBand * fStep) == (int)((iOnBand + 1) * fStep)

&& (int)((iOnBand + 1) * fStep) == (int)((iOnBand + 2)* fStep))

{

continue;

}

stepR.SetRect(rect.left, rect.top + (int)(iOnBand * fStep),

rect.right, rect.top + (int)((iOnBand + 1)* fStep));

color = RGB((GetRValue(bottom) - GetRValue(top)) * ((float)iOnBand) / 255.0f + GetRValue(top),

(GetGValue(bottom) - GetGValue(top)) * ((float)iOnBand) / 255.0f + GetGValue(top),

(GetBValue(bottom) - GetBValue(top)) * ((float)iOnBand) / 255.0f + GetBValue(top));

pdc->FillSolidRect(stepR,color);

}

}

以上代码从网上搜集

//调用例子

void test()

{

//蓝色

COLORREF midClr = RGB(147,255,255);//RGB(187,222,222);

COLORREF bianClr = RGB(49,68,212);//RGB(80,80,180);

//    //红色

// midClr = RGB(252,200,200);

// bianClr = RGB(255,80,80);

RECT rect = {180,10,240,179};

HDC hdc=::GetDC(m_hWnd);

int w = (rect.right - rect.left);

RECT rect1=rect;

rect1.right = rect1.left + w / 2;

DrawGradientH(hdc,bianClr,midClr,rect1);

RECT rect2=rect;

rect2.left = rect1.right;

DrawGradientH(hdc,midClr,bianClr,rect2);

::ReleaseDC(m_hWnd,hdc);

}

转载于:https://my.oschina.net/abcMx/blog/187998