GDI +字体渲染，尤其是在分层窗口中。

| 我的朋友们，这将是一个漫长的... 当我尝试在分层窗口中渲染文本时，我得到一些非常奇怪的行为。奇怪的是，对于字体/字体样式/字体大小的某些组合，GDI +更改了呈现方法。对于Tahoma-Bold字体，字体大小在8.49和16.49（像素单位）之间（包括“失败”）。对于其他字体和样式，我得到不同大小的“失败”字样。为了清楚起见，我在下面提供了完整的可执行示例。第23行显示两个要使用的关键参数：

Color g_oTextColor( 255, 240, 0, 0 ); // Simply change Color to ( 254, 240, 0, 0 ) [to add slight transparency] and everything will work!
#define USE_LAYERED_WINDOW // or just comment this line out [to use a regular window], and everything will work!

当使用分层窗口和完全不透明时，字体在背景中绘制一个透明的“孔”。但是，如果我为文本颜色添加了一点透明度（alpha通道= 254），则字体会变得不透明。或者，如果我使用常规（非分层）窗口，则字体会变得不透明。这里发生了什么？？但是即使没有分层/透明性问题，也很明显这里发生了一些奇怪的事情。字体大小为8.49-16.48的字体可完美呈现像素，其他字体则具有轻微的模糊质量，尤其是较小的字体。因此，似乎系统采用了不同的方法来呈现这些中等大小。有人可以对此有所了解吗，如何在不出现上述模糊的情况下渲染例如8.0像素的字体？我已经尝试过各种用于SetTextRenderingHint()和SetTextContrast()的设置，但是对于8号字体来说，它们看起来都不清晰。我只尝试了Tahoma＆Arial ... 补充问题1：我想使用纯GDI +进行屏幕外绘图，但仅创建Bitmap和Graphics对象就无法使其工作。我仍然必须使用旧的GDI东西来创建DC并在其中选择HBitmap。如何在GDI +中完成所有操作？补充问题2（仅适用于极客）：我还尝试使用陈旧的GDI绘制字体，但是我得到了一些更加奇怪的效果：（1）在分层的窗口中，文本变得透明，但是以加法的方式。（因此，如果后面的窗口是黑暗的，但如果后面的窗口是白色，则红色文本看起来会很好，但文本会完全消失！）此外，如果我在自己的窗口中填充了半透明的正方形，则其行为将符合预期。（如果红色方格后面的窗口为黑色，则红色方格将变为深红色，而白色方格上的红色方格将变为浅红色）。而且我可以在一个分层的窗口中同时观察这两种行为。（2）作为高度不希望的奖励，绘制的文本丢失了它的命中测试，变得无法点击了吗？有什么解释吗？如果您已读完本文，则感谢您的耐心等待，也感谢您的任何回答！

// Create as a console application project
// + Unicode charset
// + Precompiled headers off
// + make sure to add linker input: gdiplus.lib

#ifndef _WIN32_WINNT        // Allow use of features specific to Windows XP or later.                   
#define _WIN32_WINNT 0x0501 // Change this to the appropriate value to target other versions of Windows.
#endif                      

// Standard and GDI+ stuffstuff 
#include <stdio.h>
#include <tchar.h>
#include <windows.h>
#include <iostream>
#include <cassert>
#include <Gdiplus.h>
using namespace Gdiplus;
GdiplusStartupInput g_oGdiPlusStartupInput;
ULONG_PTR g_pGdiPlusToken = NULL;


// #*#*#*#*#*#*#*#*# LINES TO CHANGE ---------->---------->---------->
Color g_oTextColor( 255, 240, 0, 0 ); // Simply change Color to ( 254, 240, 0, 0 ) [to add slight transparency] and everything will work!
#define USE_LAYERED_WINDOW // or just comment this line out [to use a regular window], and everything will work!


// Forward declarations
void RegWndClass();
LRESULT CALLBACK WndProc( HWND hWnd, UINT uiMsg, WPARAM wParam, LPARAM lParam );
void CreateWindows();
void Draw();
void MsgLoop();

// Other Globals
ATOM g_iWndClass = 0;
HWND g_hWndGdiPlus = NULL;
HWND g_hWndGdi = NULL;
const wchar_t* g_pWndClass = L\"TST\";
int g_iWidth = 200;
int g_iHeight = 200;

// Main entry-point
int _tmain( int argc, _TCHAR* argv[] )
{
    GdiplusStartup( &g_pGdiPlusToken, &g_oGdiPlusStartupInput, NULL );

    RegWndClass();
    CreateWindows();
    Draw();

    MsgLoop();

    ::UnregisterClass( g_pWndClass, NULL );
    ::Sleep( 500 );


    GdiplusShutdown( g_pGdiPlusToken );

    return 0;
} // _tmain

void CreateWindows()
{
#ifdef USE_LAYERED_WINDOW
        // The key trick is to create a window with style WS_EX_LAYERED, but WITHOUT any subsequent calls to SetLayeredWindowAttributes()
        // This gives us a magic window that must be updated with UpdateLayeredWindow() ( and it does NOT recieve any WM_PAINT messages )
        // as brilliantly described in: http://alexkr.com/source-code/50/layered-windows-and-updatelayeredwindow/
        g_hWndGdiPlus = ::CreateWindowEx( WS_EX_LAYERED, g_pWndClass, L\"\", WS_POPUP | WS_VISIBLE, 1000, 200, g_iWidth, g_iHeight, NULL, NULL, NULL, NULL ); 
#else
        g_hWndGdiPlus = ::CreateWindowEx( 0, g_pWndClass, L\"\", WS_OVERLAPPEDWINDOW | WS_POPUP | WS_VISIBLE, 1000, 200, g_iWidth, g_iHeight, NULL, NULL, NULL, NULL ); 
#endif

    //g_hWndGdi = ::CreateWindowEx( WS_EX_LAYERED, g_pWndClass, L\"\", WS_POPUP | WS_VISIBLE, 720, 500, 200, 200, NULL, NULL, NULL, NULL ); 

} // CreateWindows

void Draw()
{
    // Init GDI+ surface
    HDC hOff = ::CreateCompatibleDC( NULL );
    Bitmap oDaBigOne( g_iWidth, g_iHeight, PixelFormat32bppARGB );
    HBITMAP hBMit =  NULL;
    Color oCol( 0, 0, 0, 0 );
    oDaBigOne.GetHBITMAP( oCol, &hBMit );
    HGDIOBJ hSave = ::SelectObject( hOff, hBMit );

#ifdef USE_LAYERED_WINDOW
        Graphics oGraph( hOff );
#else
        Graphics oGraph( g_hWndGdiPlus );
#endif

    oGraph.Clear( Color( 255, 55, 155, 255 ) );

    // Draw text
    oGraph.SetTextRenderingHint( TextRenderingHintAntiAliasGridFit );
    oGraph.SetTextContrast( 0xffffffff );
    oGraph.SetCompositingMode( CompositingModeSourceOver );
    oGraph.SetCompositingQuality( CompositingQualityHighQuality );
    oGraph.SetPixelOffsetMode( PixelOffsetModeHighQuality );

    const FontFamily oFamily( L\"Tahoma\", NULL );

#if 1 // Use bold
    Font oF600( &oFamily, 6.00, FontStyle::FontStyleBold, Unit::UnitPixel );
    Font oF800( &oFamily, 8.00, FontStyle::FontStyleBold, Unit::UnitPixel );
    Font oF848( &oFamily, 8.48, FontStyle::FontStyleBold, Unit::UnitPixel );
    Font oF849( &oFamily, 8.49, FontStyle::FontStyleBold, Unit::UnitPixel );
    Font oF1200( &oFamily, 12.00, FontStyle::FontStyleBold, Unit::UnitPixel );
    Font oF1500( &oFamily, 15.00, FontStyle::FontStyleBold, Unit::UnitPixel );
    Font oF1648( &oFamily, 16.48, FontStyle::FontStyleBold, Unit::UnitPixel );
    Font oF1649( &oFamily, 16.49, FontStyle::FontStyleBold, Unit::UnitPixel );
#else // Use regular
    Font oF600( &oFamily, 6.00, FontStyle::FontStyleRegular, Unit::UnitPixel );
    Font oF800( &oFamily, 8.00, FontStyle::FontStyleRegular, Unit::UnitPixel );
    Font oF848( &oFamily, 8.48, FontStyle::FontStyleRegular, Unit::UnitPixel );
    Font oF849( &oFamily, 8.49, FontStyle::FontStyleRegular, Unit::UnitPixel );
    Font oF1200( &oFamily, 12.00, FontStyle::FontStyleRegular, Unit::UnitPixel );
    Font oF1500( &oFamily, 15.00, FontStyle::FontStyleRegular, Unit::UnitPixel );
    Font oF1648( &oFamily, 16.48, FontStyle::FontStyleRegular, Unit::UnitPixel );
    Font oF1649( &oFamily, 16.49, FontStyle::FontStyleRegular, Unit::UnitPixel );
#endif

    assert( oF600.GetLastStatus() == Ok ); // Make sure font is OK

    SolidBrush oBrush( g_oTextColor ); 

    double dy = 1.0;
    oGraph.DrawString( L\"Size 6.00\", -1, &oF600, PointF( 30.0, dy += 18.0 ), &oBrush );
    oGraph.DrawString( L\"Size 8.00\", -1, &oF800, PointF( 30.0, dy += 18.0 ), &oBrush );
    oGraph.DrawString( L\"Size 8.48\", -1, &oF848, PointF( 30.0, dy += 18.0 ), &oBrush );
    oGraph.DrawString( L\"Size 8.49\", -1, &oF849, PointF( 30.0, dy += 18.0 ), &oBrush );
    oGraph.DrawString( L\"Size 12.00\", -1, &oF1200, PointF( 30.0, dy += 18.0 ), &oBrush );
    oGraph.DrawString( L\"Size 15.00\", -1, &oF1500, PointF( 30.0, dy += 18.0 ), &oBrush );
    oGraph.DrawString( L\"Size 16.48\", -1, &oF1648, PointF( 30.0, dy += 18.0 ), &oBrush );
    oGraph.DrawString( L\"Size 16.49\", -1, &oF1649, PointF( 30.0, dy += 18.0 ), &oBrush );

#ifndef USE_LAYERED_WINDOW
    return;
#endif

    // Do da layered window magic stuff
    BLENDFUNCTION oBF = { 0 };
    oBF.BlendOp = AC_SRC_OVER;
    oBF.BlendFlags = 0;
    oBF.SourceConstantAlpha = 255;
    oBF.AlphaFormat = AC_SRC_ALPHA;

    SIZE oSize = { 0 };
    oSize.cx = g_iWidth;
    oSize.cy = g_iHeight;

    POINT oPTZero = { 0 };

    RECT oRect = { 0 };
    ::GetWindowRect( g_hWndGdiPlus, &oRect );

    POINT oPTWnd = { 0 };

    oPTWnd.x = oRect.left;
    oPTWnd.y = oRect.top;

    //HDC hDC = oGraph.GetHDC();
    BOOL bOK = ::UpdateLayeredWindow( g_hWndGdiPlus,
        NULL, //HDC hdcDst,
        &oPTWnd, // POINT &oPtNull,
        &oSize, // SIZE *psize,
        hOff, // HDC hdcSrc,
        &oPTZero, // POINT *pptSrc,
        RGB(255,255,255), // COLORREF crKey,
        &oBF, // BLENDFUNCTION *pblend,
        ULW_ALPHA // DWORD dwFlags
    );
} // Draw

void MsgLoop()
{
    ::SetTimer( g_hWndGdiPlus, 0, 19999, NULL ); // Self-destruct timer

    MSG msg = { 0 };
    while ( ::GetMessage( &msg, NULL, 0, 0 ) )
    {
            ::TranslateMessage(&msg);
            ::DispatchMessage(&msg);
    }
} // MsgLoop

void RegWndClass()
{

        WNDCLASSEX wcex = { 0 };

        wcex.cbSize          = sizeof(WNDCLASSEX);
        wcex.style           = CS_HREDRAW | CS_VREDRAW | CS_OWNDC;
        wcex.lpfnWndProc     = WndProc;
        wcex.cbClsExtra      = 0;
        wcex.cbWndExtra      = 8; // 8 bytes, to allow for 64-bit architecture
        wcex.hInstance       = NULL; // CHECK
        wcex.hIcon           = NULL;
        wcex.hCursor         = ::LoadCursor(NULL, IDC_ARROW);
        wcex.hbrBackground   = (HBRUSH)NULL_BRUSH; // CHECK
        wcex.lpszMenuName    = NULL;
        wcex.lpszClassName   = g_pWndClass;
        wcex.hIconSm         = NULL;

        g_iWndClass = ::RegisterClassEx(&wcex);
} // RegWndClass

LRESULT CALLBACK WndProc( HWND hWnd, UINT uiMsg, WPARAM wParam, LPARAM lParam )
{
    switch( uiMsg )
    {
        case WM_TIMER:
        {
            std::wstring s;
            std::wcout <<  L\"Let´s quit\" ;
            ::PostQuitMessage( 0 );
            return 0;
        }
        case WM_PAINT:
            Draw();
            break;

        default:
        {
            return DefWindowProc( hWnd, uiMsg, wParam, lParam );
        }
    }
    return DefWindowProc( hWnd, uiMsg, wParam, lParam );
} // WndProc

[编辑]问题解决了！根据Rodrogo的出色建议，编写以下代码。感谢他，并深表感谢。我真的很感激所有编辑都标记为//＃MOD

// Create as a console application project
// + Unicode charset
// + Precompiled headers off
// + make sure to add linker input: gdiplus.lib

#ifndef _WIN32_WINNT        // Allow use of features specific to Windows XP or later.                   
#define _WIN32_WINNT 0x0501 // Change this to the appropriate value to target other versions of Windows.
#endif                      

// Standard stuff
#include <stdio.h>
#include <tchar.h>
#include <windows.h>
#include <iostream>
#include <cassert>

// GDI+ stuff
#include <Gdiplus.h>
using namespace Gdiplus;
GdiplusStartupInput g_oGdiPlusStartupInput;
ULONG_PTR g_pGdiPlusToken = NULL;




// #*#*#*#*#*#*#*#*# LINES TO CHANGE ---------->---------->---------->
Color g_oTextColor( 255, 240, 0, 0 ); // Simply change Color to ( 254, 240, 0, 0 ) [to add slight transparency] and everything will work!
#define USE_LAYERED_WINDOW // or just omment this line [to use a regular window], and everything will work!






// Forward declarations
void RegWndClass();
LRESULT CALLBACK WndProc( HWND hWnd, UINT uiMsg, WPARAM wParam, LPARAM lParam );
void CreateWindows();
void Draw();
void MsgLoop();

// Other Globals
ATOM g_iWndClass = 0;
HWND g_hWndGdiPlus = NULL;
HWND g_hWndGdi = NULL;
const wchar_t* g_pWndClass = L\"TST\";
int g_iWidth = 200;
int g_iHeight = 200;

// Main entry-point
int _tmain( int argc, _TCHAR* argv[] )
{
    GdiplusStartup( &g_pGdiPlusToken, &g_oGdiPlusStartupInput, NULL );

    RegWndClass();
    CreateWindows();
    Draw();

    MsgLoop();

    ::UnregisterClass( g_pWndClass, NULL );
    ::Sleep( 500 );


    GdiplusShutdown( g_pGdiPlusToken );

    return 0;
} // _tmain

void CreateWindows()
{
#ifdef USE_LAYERED_WINDOW
        // The key trick is to create a window with style WS_EX_LAYERED, but WITHOUT any subsequent calls to SetLayeredWindowAttributes()
        // This gives us a magic window that must be updated with UpdateLayeredWindow() ( and it does NOT recieve any WM_PAINT messages )
        // as brilliantly described in: http://alexkr.com/source-code/50/layered-windows-and-updatelayeredwindow/
        g_hWndGdiPlus = ::CreateWindowEx( WS_EX_LAYERED, g_pWndClass, L\"\", WS_POPUP | WS_VISIBLE, 1000, 200, g_iWidth, g_iHeight, NULL, NULL, NULL, NULL ); 
#else
        g_hWndGdiPlus = ::CreateWindowEx( 0, g_pWndClass, L\"\", WS_OVERLAPPEDWINDOW | WS_POPUP | WS_VISIBLE, 1000, 200, g_iWidth, g_iHeight, NULL, NULL, NULL, NULL ); 
#endif

    //g_hWndGdi = ::CreateWindowEx( WS_EX_LAYERED, g_pWndClass, L\"\", WS_POPUP | WS_VISIBLE, 720, 500, 200, 200, NULL, NULL, NULL, NULL ); 

} // CreateWindows

void Draw()
{
    // Init GDI+ surface
    HDC hOff = ::CreateCompatibleDC( NULL );
    Bitmap oDaBigOne( g_iWidth, g_iHeight, PixelFormat32bppARGB );
    HBITMAP hBMit =  NULL;
    Color oCol( 0, 0, 0, 0 );
    // oDaBigOne.GetHBITMAP( oCol, &hBMit ); //#MOD
    // HGDIOBJ hSave = ::SelectObject( hOff, hBMit ); //#MOD


    { // Limit oGraph scope //#MOD
#ifdef USE_LAYERED_WINDOW
        //Graphics oGraph( hOff ); //#MOD
        Graphics oGraph( &oDaBigOne ); //#MOD
#else
        Graphics oGraph( g_hWndGdiPlus );
#endif

    oGraph.Clear( Color( 255, 55, 155, 255 ) );

    // Draw text
    oGraph.SetTextRenderingHint( TextRenderingHintAntiAliasGridFit );
    oGraph.SetCompositingMode( CompositingModeSourceOver );
    oGraph.SetCompositingQuality( CompositingQualityHighQuality );
    oGraph.SetPixelOffsetMode( PixelOffsetModeHighQuality );

    const FontFamily oFamily( L\"Tahoma\", NULL );

#if 1 // Use bold
    Font oF600( &oFamily, 6.00, FontStyle::FontStyleBold, Unit::UnitPixel );
    Font oF848( &oFamily, 8.48, FontStyle::FontStyleBold, Unit::UnitPixel );
    Font oF849( &oFamily, 8.49, FontStyle::FontStyleBold, Unit::UnitPixel );
    Font oF1200( &oFamily, 12.00, FontStyle::FontStyleBold, Unit::UnitPixel );
    Font oF1500( &oFamily, 15.00, FontStyle::FontStyleBold, Unit::UnitPixel );
    Font oF1648( &oFamily, 16.48, FontStyle::FontStyleBold, Unit::UnitPixel );
    Font oF1649( &oFamily, 16.49, FontStyle::FontStyleBold, Unit::UnitPixel );
#else // Use regular
    Font oF600( &oFamily, 6.00, FontStyle::FontStyleRegular, Unit::UnitPixel );
    Font oF848( &oFamily, 8.48, FontStyle::FontStyleRegular, Unit::UnitPixel );
    Font oF849( &oFamily, 8.49, FontStyle::FontStyleRegular, Unit::UnitPixel );
    Font oF1200( &oFamily, 12.00, FontStyle::FontStyleRegular, Unit::UnitPixel );
    Font oF1500( &oFamily, 15.00, FontStyle::FontStyleRegular, Unit::UnitPixel );
    Font oF1648( &oFamily, 16.48, FontStyle::FontStyleRegular, Unit::UnitPixel );
    Font oF1649( &oFamily, 16.49, FontStyle::FontStyleRegular, Unit::UnitPixel );
#endif

    assert( oF600.GetLastStatus() == Ok ); // Make sure font is OK

    SolidBrush oBrush( g_oTextColor ); 

    double dy = 10.0;
    oGraph.DrawString( L\"Size 6.00\", -1, &oF600, PointF( 30.0, dy += 18.0 ), &oBrush );
    oGraph.DrawString( L\"Size 8.48\", -1, &oF848, PointF( 30.0, dy += 18.0 ), &oBrush );
    oGraph.DrawString( L\"Size 8.49\", -1, &oF849, PointF( 30.0, dy += 18.0 ), &oBrush );
    oGraph.DrawString( L\"Size 12.00\", -1, &oF1200, PointF( 30.0, dy += 18.0 ), &oBrush );
    oGraph.DrawString( L\"Size 15.00\", -1, &oF1500, PointF( 30.0, dy += 18.0 ), &oBrush );
    oGraph.DrawString( L\"Size 16.48\", -1, &oF1648, PointF( 30.0, dy += 18.0 ), &oBrush );
    oGraph.DrawString( L\"Size 16.49\", -1, &oF1649, PointF( 30.0, dy += 18.0 ), &oBrush );

#ifndef USE_LAYERED_WINDOW
    return;
#endif
    } // Limit oGraph scope //#MOD

    // Do da layered window magic stuff
    BLENDFUNCTION oBF = { 0 };
    oBF.BlendOp = AC_SRC_OVER;
    oBF.BlendFlags = 0;
    oBF.SourceConstantAlpha = 255;
    oBF.AlphaFormat = AC_SRC_ALPHA;

    SIZE oSize = { 0 };
    oSize.cx = g_iWidth;
    oSize.cy = g_iHeight;

    POINT oPTZero = { 0 };

    RECT oRect = { 0 };
    ::GetWindowRect( g_hWndGdiPlus, &oRect );

    POINT oPTWnd = { 0 };

    oPTWnd.x = oRect.left;
    oPTWnd.y = oRect.top;

    oDaBigOne.GetHBITMAP( oCol, &hBMit ); //#MOD
    HGDIOBJ hSave = ::SelectObject( hOff, hBMit ); //#MOD

    //HDC hDC = oGraph.GetHDC();
    BOOL bOK = ::UpdateLayeredWindow( g_hWndGdiPlus,
        NULL, //HDC hdcDst,
        &oPTWnd, // POINT &oPtNull,
        &oSize, // SIZE *psize,
        hOff, // HDC hdcSrc,
        &oPTZero, // POINT *pptSrc,
        RGB(255,255,255), // COLORREF crKey,
        &oBF, // BLENDFUNCTION *pblend,
        ULW_ALPHA // DWORD dwFlags
    );
} // Draw

void MsgLoop()
{
    ::SetTimer( g_hWndGdiPlus, 0, 19999, NULL ); // Self-destruct timer

    MSG msg = { 0 };
    while ( ::GetMessage( &msg, NULL, 0, 0 ) )
    {
            ::TranslateMessage(&msg);
            ::DispatchMessage(&msg);
    }
} // MsgLoop

void RegWndClass()
{

        WNDCLASSEX wcex = { 0 };

        wcex.cbSize          = sizeof(WNDCLASSEX);
        wcex.style           = CS_HREDRAW | CS_VREDRAW | CS_OWNDC;
        wcex.lpfnWndProc     = WndProc;
        wcex.cbClsExtra      = 0;
        wcex.cbWndExtra      = 8; // 8 bytes, to allow for 64-bit architecture
        wcex.hInstance       = NULL; // CHECK
        wcex.hIcon           = NULL;
        wcex.hCursor         = ::LoadCursor(NULL, IDC_ARROW);
        wcex.hbrBackground   = (HBRUSH)NULL_BRUSH; // CHECK
        wcex.lpszMenuName    = NULL;
        wcex.lpszClassName   = g_pWndClass;
        wcex.hIconSm         = NULL;

        g_iWndClass = ::RegisterClassEx(&wcex);
} // RegWndClass

LRESULT CALLBACK WndProc( HWND hWnd, UINT uiMsg, WPARAM wParam, LPARAM lParam )
{
    switch( uiMsg )
    {
        case WM_TIMER:
        {
            std::wstring s;
            std::wcout <<  L\"Let´s quit\" ;
            ::PostQuitMessage( 0 );
            return 0;
        }
        case WM_PAINT:
            Draw();
            break;

        default:
        {
            return DefWindowProc( hWnd, uiMsg, wParam, lParam );
        }
    }
    return DefWindowProc( hWnd, uiMsg, wParam, lParam );
} // WndProc

已邀请:

4 个回复

癸痊醒

我认为问题在于，GDI（不带+）不能很好地支持alpha透明度。充其量，它保持alpha通道不变。当您使用具有选定位图且具有Alpha通道的HDC使用HDC构建图形对象时，事情会变得很糟。我的猜测是，光栅化的GDI +字体会根据许多参数来决定使用哪种方法进行渲染。然后，如果GDI恰好支持此方法，则将使用它（并且忽略Alpha通道）；如果GDI不支持render方法，它将回退到逐像素或类似的渲染，并且可以正确使用alpha通道。因此，为了获得正确的结果，您不应使用HDC修改Alpha通道。尝试以下更改：使用位图创建Graphics对象，而不是HDC：

Graphics oGraph( &oDaBigOne );

仅在渲染完成后，才将位图选择到HDC hOff中。为确保销毁Graphics对象，最好用{...}限制其范围。 [编辑] 使用新代码后，解决方案很容易：不仅应在绘图之后将调用移至SelectObject（），还应将GetBitmap（）移至。也就是说，这两个函数应该在：UpdateLayeredWindow（）调用之前：

oDaBigOne.GetHBITMAP( oCol, &hBMit );
HGDIOBJ hSave = ::SelectObject( hOff, hBMit );

淘圃跺枯替

我想，昨天我找到了一个（部分）解决方案，比rodrigo建议的解决方案更容易实现：您可以在传递给DrawString的StringFormat实例中简单地将StringFormatFlags::StringFormatFlagsBypassGDI指定为格式标志。瞧：一切都是使用具有Alpha功能的字体渲染器绘制的。这至少解决了Alpha通道问题。

抢垢洛韧

我暂时无法找到这种奇怪行为的解释。但是，我确实发现使用默认渲染值可以对某些字体提供更好的效果，请尝试使用以下设置进行Arial：

oGraph.SetTextRenderingHint( TextRenderingHintAntiAliasGridFit );
oGraph.SetPixelOffsetMode( PixelOffsetModeDefault );
oGraph.SetCompositingMode( CompositingModeSourceOver );
oGraph.SetCompositingQuality( CompositingQualityDefault );

寿柬窟年

尝试将PixelFormat32bppARGB换成PixelFormat32bppPARGB。 BLENDFUNCTION结构的文档指出，它需要在源文件中预乘alpha。

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GDI +字体渲染，尤其是在分层窗口中。

4 个回复

发起人

c++

rendering

fonts

gdi+

问题状态

GDI +字体渲染，尤其是在分层窗口中。

与内容相关的链接

4 个回复

发起人

c++

rendering

fonts

gdi+

问题状态