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POWin32 GDI Drawing a circle?
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14063463
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14077397
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2012-12-28T01:29:13.130
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Body
I am trying to draw a circle and I am currently using the Ellipse() function. I have the starting mouse coordinates - x1 and y1 and the ending coordinates x2 and y2. As you can see, I am forcing the y2(temp_shape.bottom) to be = y1+(x2-x1). This doesn't work as intended. I know the calculation is completely wrong but any ideas on what is right? Code Below. <pre><code>case WM_PAINT: { hdc = BeginPaint(hWnd, &ps); // TODO: Add any drawing code here... RECT rect; GetClientRect(hWnd, &rect); HDC backbuffDC = CreateCompatibleDC(hdc); HBITMAP backbuffer = CreateCompatibleBitmap( hdc, rect.right, rect.bottom); int savedDC = SaveDC(backbuffDC); SelectObject( backbuffDC, backbuffer ); HBRUSH hBrush = CreateSolidBrush(RGB(255,255,255)); FillRect(backbuffDC,&rect,hBrush); DeleteObject(hBrush); //Brush and Pen colours SelectObject(backbuffDC, GetStockObject(DC_BRUSH)); SetDCBrushColor(backbuffDC, RGB(255,0,0)); SelectObject(backbuffDC, GetStockObject(DC_PEN)); SetDCPenColor(backbuffDC, RGB(0,0,0)); //Shape Coordinates temp_shape.left=x1; temp_shape.top=y1; temp_shape.right=x2; temp_shape.bottom=y2; //Draw Old Shapes //Rectangles for ( int i = 0; i < current_rect_count; i++ ) { Rectangle(backbuffDC, rect_list[i].left, rect_list[i].top, rect_list[i].right, rect_list[i].bottom); } //Ellipses for ( int i = 0; i < current_ellipse_count; i++ ) { Ellipse(backbuffDC, ellipse_list[i].left, ellipse_list[i].top, ellipse_list[i].right, ellipse_list[i].bottom); } if(mouse_down) { if(drawCircle) { temp_shape.right=y1+(x2-x1); Ellipse(backbuffDC, temp_shape.left, temp_shape.top, temp_shape.right, temp_shape.bottom); } if(drawRect) { Rectangle(backbuffDC, temp_shape.left, temp_shape.top, temp_shape.right, temp_shape.bottom); } if(drawEllipse) { Ellipse(backbuffDC, temp_shape.left, temp_shape.top, temp_shape.right, temp_shape.bottom); } } BitBlt(hdc,0,0,rect.right,rect.bottom,backbuffDC,0,0,SRCCOPY); RestoreDC(backbuffDC,savedDC); DeleteObject(backbuffer); DeleteDC(backbuffDC); EndPaint(hWnd, &ps); } break; </code></pre>
Tags
<c++><gdi><win32gui>
Title
Win32 GDI Drawing a circle?
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