来源（Iczelion's win32 asm tutorial）[article from asm.yeah.net] Tutorial 5: More about Text
We will experiment more with text attributes, ie. font and color.
Download the example file here.
Theory:Windows color system is based on RGB values, R=red, G=Green, B=Blue. If you want to specify a color in Windows, you must state your desired color in terms of these three major colors. Each color value has a range from 0 to 255 (a byte value). For example, if you want pure red color, you should use 255,0,0. Or if you want pure white color, you must use 255,255,255. You can see from the examples that getting the color you need is very difficult with this system since you have to have a good grasp of how to mix and match colors.
For text color and background, you use SetTextColor and SetBkColor, both of them require a handle to device context and a 32-bit RGB value. The 32-bit RGB value's structure is defined as:
Note that the first byte is not used and should be zero. The order of the remaining three bytes is reversed,ie. blue, green, red. However, we will not use this structure since it's cumbersome to initialize and use. We will create a macro instead. The macro will receive three parameters: red, green and blue values. It'll produce the desired 32-bit RGB value and store it in eax. The macro is as follows:
RGB macro red,green,blue
You can put this macro in the include file for future use.
WinMain proto :DWORD,:DWORD,:DWORD,:DWORD
RGB macro red,green,blue
WndProc proc hWnd:HWND, uMsg:UINT, wParam:WPARAM, lParam:LPARAM
DEFAULT_QUALITY,DEFAULT_PITCH or FF_SCRIPT,\
CreateFont creates a logical font that is the closest match to the given parameters and the font data available. This function has more parameters than any other function in Windows. It returns a handle to logical font to be used by SelectObject function. We will examine its parameters in detail.
CreateFont proto nHeight:DWORD,\
nHeight The desired height of the characters . 0 means use
FW_THIN equ 100
FW_EXTRALIGHT equ 200
FW_ULTRALIGHT equ 200
FW_LIGHT equ 300
FW_NORMAL equ 400
FW_REGULAR equ 400
FW_MEDIUM equ 500
FW_SEMIBOLD equ 600
FW_DEMIBOLD equ 600
FW_BOLD equ 700
FW_EXTRABOLD equ 800
FW_ULTRABOLD equ 800
FW_HEAVY equ 900
FW_BLACK equ 900
cUnderline 0 for normal, any other value for underlined characters.
cStrikeOut 0 for normal, any other value for characters with a line through the center.
cCharSet The character set of the font. Normally should be OEM_CHARSET which allows Windows to select font which is operating system-dependent.
cOutputPrecision Specifies how much the selected font must be closely matched to the characteristics we want. Normally should be OUT_DEFAULT_PRECIS which defines default font mapping behavior.
cClipPrecision Specifies the clipping precision. The clipping precision defines how to clip characters that are partially outside the clipping region. You should be able to get by with CLIP_DEFAULT_PRECIS which defines the default clipping behavior.
cQuality Specifies the output quality. The output quality defines how carefully GDI must attempt to match the logical-font attributes to those of an actual physical font. There are three choices: DEFAULT_QUALITY, PROOF_QUALITY and DRAFT_QUALITY.
cPitchAndFamily Specifies pitch and family of the font. You must combine the pitch value and the family value with "or" operator.
lpFacename A pointer to a null-terminated string that specifies the typeface of the font.
The description above is by no means comprehensive. You should refer to your Win32 API reference for more details.
invoke SelectObject, hdc, eax
After we get the handle to the logical font, we must use it to select the font into the device context by calling SelectObject. SelectObject puts the new GDI objects such as pens, brushs, and fonts into the device context to be used by GDI functions. It returns the handle to the replaced object which we should save for future SelectObject call. After SelectObject call, any text output function will use the font we just selected into the device context.
Use RGB macro to create a 32-bit RGB value to be used by SetColorText and SetBkColor.
invoke TextOut,hdc,0,0,ADDR TestString,SIZEOF TestString
Call TextOut function to draw the text on the client area. The text will be in the font and color we specified previously.
invoke SelectObject,hdc, hfont
When we are through with the font, we should restore the old font back into
the device context. You should always restore the object that you replaced in
the device context.