VCL.Graphex Sample

This sample demonstrates how to create a simple graphical editor.

Location

You can find the Graphex sample project at:

• Start > Programs > Embarcadero RAD Studio > Samples and then navigate to either:
  • Delphi\VCL\Graphex
  • CPP\VCL\Graphex
• Subversion Repository for Delphi: http://sourceforge.net/p/radstudiodemos/code/HEAD/tree/branches/RadStudio_XE4/Delphi/VCL/Graphex/
• Subversion Repository for C++: http://sourceforge.net/p/radstudiodemos/code/HEAD/tree/branches/RadStudio_XE4/CPP/VCL/Graphex/

Description

The application creates a simple graphic editor that provides basic graphic functionality: drawing shapes (lines, rectangles, ellipses, round rectangles), changing the type, width, and color of lines and hatches. It also provides basic File actions: creating, saving and opening an image, and Edit actions: copying, cutting, and pasting.

How to Use the Sample

1. Navigate to Start > Programs > Embarcadero RAD Studio > Samples and open graphex.dproj.
2. Press F9 or choose Run > Run.

Files

File	Contains
BMPDlg	The class for the form that is displayed when the user chooses File > New from the graphic editor.
GraphWin	The class for the main form that represents the editor itself.

Classes

• TNewBMPForm is the class for the form that is displayed when you want to create a new image. You can use this form to choose the size of the new canvas.
• TForm1 is the class for the main form. It contains toolbars, a menu bar, and a TImage component as the drawing surface. It also contains dialog components for displaying open, save, and color dialogs. The toolbars are actually panels with customized TSpeedButton components.

Implementation

• To draw the selected shape in real time, the pmNotXor pen mode is used. This draws the shape corresponding to the new mouse position and erases the previous one.
• To copy images to the clipboard, TClipboard.Assign is used.
• Before pasting the content of the clipboard on canvas, HasFormat is used to verify if it is in bitmap format.
• To access the drawing surface of the TImage component, the TImage.Canvas property is used.
• To paint different shapes on the canvas, a variety of properties, methods, and types are used: TCanvas.Brush, TCanvas.Pen, TCanvas.Draw, TBrushStyle, TPenStyle, TCanvas.MoveTo, TCanvas.Rectangle, TCanvas.LineTo, TCanvas.Ellipse, TCanvas.RoundRect.

Uses

• TImage
• TImage.Canvas
• TSpeedButton
• TCanvas.Brush
• TCanvas.Pen
• TCanvas.Draw
• TBrushStyle
• TPenStyle
• TPenMode
• TCanvas.MoveTo
• TCanvas.Rectangle
• TCanvas.LineTo
• TCanvas.Ellipse
• TCanvas.RoundRect
• TClipboard.HasFormat
• TClipboard.Assign

See Also

• Adding a Speed Button to a Panel
• Working with Graphics and Multimedia Index
• Overview of Graphics Programming
• Copy Mode Constants
• VCL.Direct2D Sample