我的 friend 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，我会收到不同大小的“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!
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 channel = 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。 这是怎么回事？
但是即使没有分层/透明性问题，也很明显这里发生了奇怪的事情。字体大小为8.49-16.48的字体可完美呈现像素，其他字体的质量则略有模糊，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。 有人可以对此进行说明吗，如何在没有上述模糊性的情况下渲染例如8.0像素的字体？ 我已经尝试了
SetTextRenderingHint()和SetTextContrast()的各种设置，但是对于8号字体来说，它们看起来都不太清晰。我只尝试了Tahoma＆Arial ...附带问题1:
我想使用纯GDI +进行屏幕外绘图，但仅创建
Bitmap和Graphics对象就无法使其正常工作。我仍然必须使用旧的GDI东西来创建DC并选择HBitmap。如何在GDI +中完成所有操作？附带问题2(仅适用于极客):
我也尝试过使用旧的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，但是以加法方式。 (因此，如果后面的窗口很暗，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，则其行为将达到预期的效果。 (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到这两种行为。以及(2)作为高度不受欢迎的奖励，绘制的文本丢失了它的 HitTest ，变得无法点击了吗？ 那里有什么解释吗？
如果您已经阅读了本文，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
[EDIT]问题已解决!
下面的代码根据Rodrogo´s的出色建议。
衷心感谢他。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
最佳答案
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 channel 不变。
当您使用具有选定位图且具有Alpha channel 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，则将使用该方法(忽略Alpha channel )；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 channel 。
因此，为了获得正确的结果，您不应使用HDC修改Alpha channel 。尝试以下更改:
Graphics oGraph( &oDaBigOne );
[编辑]
使用新代码后，解决方案很容易:不仅应在绘图后将调用移至SelectObject()，还应将调用移至GetBitmap()。也就是说，这两个函数应该刚好在调用:UpdateLayeredWindow()之前:
oDaBigOne.GetHBITMAP( oCol, &hBMit );
HGDIOBJ hSave = ::SelectObject( hOff, hBMit );
关于c++ - GDI +字体渲染，尤其是在分层窗口中，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/5647322/