The IDE features a custom Color Dialog box to select the foreground and background colors for Ocx controls and Forms. The Color Dialog box is also used to select the editor’s syntax colors in the GB32’s Properties dialog box. Using the Color Dialog box you can select any color you want. However, the Color Dialog box presents a custom color palette for a quick selection. In addition the dialog box displays the system colors as they are defined on your version of Windows.
The Color Dialog box
The following picture displays the Color Dialog box after selecting the ForeColor property of a Form (frm1) in the form-editor. This dialog box will also be displayed after selecting the BackColor property.
The ForeColor property shows a color value of $80000008, which means that the color is set to the system color with index 8 (COLOR_WINDOWTEXT). The ForeColor property is used as the foreground color for drawing in the client area of the form.
The Color Dialog displays the 25 system colors in the lower two rows of the dialog box and it draws a focus rectangle around the color-cell that shows the system color for COLOR_WINDOWTEXT. The large cell at bottom-right of the dialog box displays the selected color. By clicking on the large box GB32 shows the common dialog’s color dialog box. The top 4 rows display a palette of often used RGB colors to allow a quick selection of a color. The fourth row also contains 8 additional colors otherwise not found in the 4 upper rows of the dialog’s color palette.
The BackColor property defines the color used to draw the (empty) contents of the client area. By default, GFA-BASIC 32 uses the system color COLOR_BTNFACE, the system color that is used to paint the shading of the face of command buttons. However, this system color is used for more UI-elements than just the shadow of the face of a button. By using the color-value $8000000f the window background gets the default color of a dialog box, so that the GB32 form will look consistently with system dialog boxes.
Using system colors
It is a big advantage that GFA-BASIC 32 let you use system colors for the user-interface elements of the form and Ocx-controls. The system colors may change when a custom Windows theme is installed or when Microsoft changes the system colors with a new release of Windows. Whenever the system colors change, the colors of the form change accordingly, providing a consistent look with the OS.
GFA-BASIC 32 distinguishes between a pure RGB color format and a system color by setting the high-bit of the 32-bit color value (Long). When a Long value is displayed in it’s hexadecimal format the high-bit setting is shown as $80000000. Before actually applying a color GB32 tests the high-bit of the color value and selects a system color when it is set:
If rgbcol %& $80000000 Then rgbcol = SysCol(rgbcol & $FF)
An application can specify a system color in two ways:
RGBColor $80000000 + COLOR_WINDOWFRAME RGBColor SysCol(COLOR_WINDOWTEXT)
The first statement sets the foreground color to a system color value. The second statement converts the system color to an RGB-value beforehand. Both statements will eventually use the RGB color that belongs to the system’s color element COLOR_WINDOWTEXT. The RGB color value for any of the display elements is obtained using the GB32’s function SysCol or the API function GetSysColor(). Each aspect of the display has its own COLOR_* constant that is used as an index in these functions. These constants are built into GFA-BASIC 32. For more information see the SysCol function in the helpfile. It explains which constant represents what user-interface element. When you hoover over the system colors in the IDE Color Dialog box it shows a short description of the display element it represents.
The Editor colors
The Editor tab in the Properties dialog box (Extra | Properties) displays the same Color Dialog box to select the syntax colors.
This picture is taken after clicking the BackColor button. It shows the selected color for the background of the “Changed/Empty” syntax (ie. the background color of empty lines and the line that is being edited). By default, the background color for all syntax elements is set to system color COLOR_WINDOW ($80000005). The foreground colors of the syntax elements are custom RGB values. By keeping the background color to a system color, the GFA-BASIC 32’s editor will adapt to the new COLOR_WINDOW color if a theme is installed.