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//===============================================================
// vMemoryDC - a memory drawing canvas - Windows
//
// Copyright (C) 1995,1996, 1997, 1998 Bruce E. Wampler
//
// This file is part of the V C++ GUI Framework, and is covered
// under the terms of the GNU Library General Public License,
// Version 2. This library has NO WARRANTY. See the source file
// vapp.cxx for more complete information about license terms.
//===============================================================
#include <v/vwin32.h>
#include <v/vmemdc.h>
#include <v/vapp.h>
//================>>> vMemoryDC::vMemoryDC <<<========================
vMemoryDC::vMemoryDC(int width, int height)
{
// Mem canvases are implemented with bitmaps. Most of the
// windows books I've seen don't seem to explain bitmaps
// very well. The idea is this. You create a bitmap (_memBM) that
// is compatible with some DC - like the app's frame DC for our
// purposes. This gives the bitmap a nice color map. Then, the
// tricky part. To use a bitmap, you have to select it into
// a DC. So, you create a new DC (_hdc) , also compatible with
// the app frame DC. Then you select the bitmap into the new
// DC. Now you can draw into the new DC. When done drawing,
// you can release/delete the memory DC until you draw again.
// When you are ALL done, finally free the bitmap. Now isn't
// that all kind of a wierd way of doing things?
_physHeight = height; // V 1.15a
_physWidth = width;
SysDebug(Constructor,"vMemoryDC::vMemoryDC() constructor\n")
if (_physWidth == 0)
_physWidth = theApp->DefaultWidth();
if (_physHeight == 0)
_physHeight = theApp->DefaultHeight();
_memBM = 0; // Not created yet
_hdc = 0;
_oldBM = 0;
}
//================>>> vMemoryDC::~vMemoryDC <<<========================
vMemoryDC::~vMemoryDC()
{
SysDebug(Destructor,"vMemoryDC::~vMemoryDC() destructor\n")
if (!_memBM)
return;
::DeleteObject(_memBM);
_memBM = 0;
}
//====================>>> vMemoryDC::GetHDC <<<========================
void vMemoryDC::GetHDC() VCONST
{
// Create the DC to draw into
HDC appDC = ::GetDC(theApp->winHwnd()); // DC of the app
if (_memBM == 0) // Need to create a bitmap
{
// Now create a bitmap
_memBM = ::CreateCompatibleBitmap(appDC,_physWidth,_physHeight);
}
if (_memBM == 0)
{
::ReleaseDC(theApp->winHwnd(),appDC);
return;
}
// Now, create an HDC for the bitmap, compatible with the app DC
_hdc = ::CreateCompatibleDC(appDC);
::ReleaseDC(theApp->winHwnd(),appDC); // Done with app's dc
_oldBM = static_cast<HBITMAP>(::SelectObject(_hdc,_memBM)); // Select into _hdc
// We are now ready to use _hdc!
}
//================>>> vMemoryDC::ReleaseHDC <<<========================
void vMemoryDC::ReleaseHDC() VCONST
{
if (_hdc == 0)
return;
::SelectObject(_hdc,_oldBM); // reselect old bm
::DeleteDC(_hdc); // free the DC
}
//=====================>>> vMemoryDC::Clear <<<==========================
void vMemoryDC::Clear(void)
{
ClearRect(0,0,_physWidth, _physHeight);
}
//==================>>> vMemoryDC::ClearRect <<<==========================
void vMemoryDC::ClearRect(int left, int top, int width, int height)
{
// Clear a rectangluar area starting at left,top of width and height
if (height == 0 || width == 0)
return;
GetHDC(); // Get a DC to use
::SetBkColor(_hdc, _canvasBG);
HBRUSH brush = ::CreateSolidBrush(_canvasBG);
RECT rect;
rect.top = top; rect.left = left;
rect.bottom = top+height; rect.right = left + width;
::FillRect(_hdc, &rect, brush);
::DeleteObject(brush); // need to free the resource!
ReleaseHDC(); // Release the DC
}
//================>>> vMemoryDC::SetBackground <<<==========================
void vMemoryDC::SetBackground(VCONST vColor& color)
{
_canvasBG = color.pixel(); // retrieve X pixel value
GetHDC();
::SetBkColor(_hdc, _canvasBG);
ReleaseHDC();
}
//======================>>> vMemoryDC::SetFont <<<===========================
void vMemoryDC::SetFont(VCONST vFont& vf)
{
// Change the font associated with this window.
_font = vf;
}
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