BCB TPanel控件透明源代码

//--------------------------------------------------------------------------- #include <vcl.h> #pragma hdrstop #include "Unit1.h" //--------------------------------------------------------------------------- #pragma package(smart_init) #pragma resource "*.dfm" TForm1 *Form1; TWndMethod PanelWndProc; //--------------------------------------------------------------------------- __fastcall TForm1::TForm1(TComponent * Owner): TForm(Owner) { Button2->Caption = "設為透明"; Button3->Caption = "設為不透明"; Button2->Enabled = TRUE; Button3->Enabled = FALSE; } //--------------------------------------------------------------------------- void DrawParentImage(TControl * Control, TCanvas * DestCanvas) { int iSaveIndex; TPoint Position; if (!Control->Parent) return; iSaveIndex = SaveDC(DestCanvas->Handle); GetViewportOrgEx(DestCanvas->Handle, & Position); SetViewportOrgEx(DestCanvas->Handle, Position.x - Control->Left, Position.y - Control->Top, NULL); IntersectClipRect(DestCanvas->Handle, 0, 0, Control->Parent->ClientWidth, Control->Parent->ClientHeight); Control->Parent->Perform(WM_ERASEBKGND, (int) DestCanvas->Handle, 0); Control->Parent->Perform(WM_PAINT, (int) DestCanvas->Handle, 0); RestoreDC(DestCanvas->Handle, iSaveIndex); } void SetPanelTransparent(TPanel * Panel, BOOL bTransparent) { Graphics::TBitmap * MemoryBitmap = new Graphics::TBitmap; try { MemoryBitmap->Width = Panel->Width; MemoryBitmap->Height = Panel->Height; if (bTransparent) // 設為透明 { // 把Panel背後的圖Copy到Memory Bitmap上. DrawParentImage(Panel, MemoryBitmap->Canvas); } else // 設為不透明 { // 填滿Panel原始底色 MemoryBitmap->Canvas->Brush->Color = Panel->Color; MemoryBitmap->Canvas->FillRect(Panel->ClientRect); } // 把Memory Bitmap 畫到Panel上. BitBlt(GetDC(Panel->Handle), 1, 1, Panel->Width - 2, Panel->Height - 2, MemoryBitmap->Canvas->Handle, 0, 0, SRCCOPY); // 避免TGraphicControl類的元件被清掉 for (int i = 0; i < Panel->ControlCount; i++) { if (Panel->Controls[i]->Visible) Panel->Controls[i]->Refresh(); } } __finally { delete MemoryBitmap; } } void __fastcall TForm1::NewPanelWndProc(Messages::TMessage & Message) { PanelWndProc(Message); if (Message.Msg == WM_PAINT) // 攔截Panel的WM_PAINT, 並把背景畫上. SetPanelTransparent(Form1->Panel1, TRUE); } //--------------------------------------------------------------------------- void __fastcall TForm1::Button2Click(TObject * Sender) { // 設為透明 // Subclass Panel1以處理WM_PAINT PanelWndProc = Panel1->WindowProc; Panel1->WindowProc = NewPanelWndProc; Panel1->Refresh(); Button2->Enabled = FALSE; Button3->Enabled = TRUE; } //--------------------------------------------------------------------------- void __fastcall TForm1::Button3Click(TObject * Sender) { // 設為不透明 // 還原Panel1原始的訊息迴圈 Panel1->WindowProc = PanelWndProc; Panel1->Refresh(); Button2->Enabled = TRUE; Button3->Enabled = FALSE; } //---------------------------------------------------------------------------