How to load, create and use (animated) cursors? (Views: 100)


Sometimes you have the need to use an animated cursor, for example when your applications are executing long operations.
This article explains how to load, create and use cursors (animated included).


To use an animated cursor you have several options: load it from a file (using LoadImage or LoadCursorFromFile), load it from a resource (using LoadCursor) or even creating the cursor at runtime (using CreateCursor).

You should implement custom cursors as resources. Rather than create the cursors at run time, use the LoadCursor, LoadCursorFromFile, or LoadImage function to avoid device dependence, to simplify localization, and to enable applications to share cursor designs.

Loading a cursor from a file
The easiest way to load a cursor from a file is by using LoadCursorFromFile.
This functions returns a handle to the loaded cursor that you should assign to your application Cursors array.

  hCur: HCURSOR;

  // Load the cursor from file
  hCur := LoadCursorFromFile(PChar('path_to_my_cursor'));
  // Assign the loaded cursor to application Cursors array. (This cursor will ave the
  // number 1 assigned to it
  // Remember that predefined cursors start at a negative index, and user defined
  // custom cursors are assigned positive indexes.
  Screen.Cursors[1] := hCur;

  // Use the cursor as you would use a built-in cursor.
  Screen.Cursor := 1;

You can also use LoadImage instead of LoadCursorFromFile like this:  

  hCur := LoadImage(0, PChar(PChar('path_to_my_cursor')), IMAGE_CURSOR, 0, 0,
Loading a cursor from a resource

Before loading a cursor from a resource it's necessary to create the resource file with the cursor to be loaded.

To do this create a file myResources.rc where you'll put the following

#define ANICURSOR 21
myCursor ANICURSOR "path_to_my_cursor"

Because Borland's resource compiler does not understand the ANICURSOR resource type, so you have to use the numeric id (21).
Compile your resource file using "brcc32 myResources.rc" and include in the unit where you'll be loading the cursor, using {$R myResources.res}

Now, you just have to load the cursor from the resource instead of loading it from a file, using:

hCur := LoadCursor(HInstance, PChar('myCursor'));
Remember that HInstance contains the instance handle of the application or library as provided by Windows. This variable it's very importante because it's the one used with many Windows API that work with current application resources.
Creating a cursor at runtime
Another way to use a cursor it's creating one at runtime. Why would you do that?
I don't know, it's your choice. I doubt you ever will create your cursors at runtime, anyway here it's way how to do it.

Define the cursor map

  // Yin cursor AND bitmask
  ANDmaskCursor: array[0..127] of byte = (
    $FF, $FC, $3F, $FF, $FF, $C0, $1F, $FF,
    $FF, $00, $3F, $FF, $FE, $00, $FF, $FF,
    $F7, $01, $FF, $FF, $F0, $03, $FF, $FF,
    $F0, $03, $FF, $FF, $E0, $07, $FF, $FF,
    $C0, $07, $FF, $FF, $C0, $0F, $FF, $FF,
    $80, $0F, $FF, $FF, $80, $0F, $FF, $FF,
    $80, $07, $FF, $FF, $00, $07, $FF, $FF,
    $00, $03, $FF, $FF, $00, $00, $FF, $FF,
    $00, $00, $7F, $FF, $00, $00, $1F, $FF,
    $00, $00, $0F, $FF, $80, $00, $0F, $FF,
    $80, $00, $07, $FF, $80, $00, $07, $FF,
    $C0, $00, $07, $FF, $C0, $00, $0F, $FF,
    $E0, $00, $0F, $FF, $F0, $00, $1F, $FF,
    $F0, $00, $1F, $FF, $F8, $00, $3F, $FF,
    $FE, $00, $7F, $FF, $FF, $00, $FF, $FF,
    $FF, $C3, $FF, $FF, $FF, $FF, $FF, $FF

  // Yin cursor XOR bitmask
  XORmaskCursor: array[0..127] of byte = (
    $00, $00, $00, $00, $00, $03, $C0, $00,
    $00, $3F, $00, $00, $00, $FE, $00, $00,
    $0E, $FC, $00, $00, $07, $F8, $00, $00,
    $07, $F8, $00, $00, $0F, $F0, $00, $00,
    $1F, $F0, $00, $00, $1F, $E0, $00, $00,
    $3F, $E0, $00, $00, $3F, $E0, $00, $00,
    $3F, $F0, $00, $00, $7F, $F0, $00, $00,
    $7F, $F8, $00, $00, $7F, $FC, $00, $00,
    $7F, $FF, $00, $00, $7F, $FF, $80, $00,
    $7F, $FF, $E0, $00, $3F, $FF, $E0, $00,
    $3F, $C7, $F0, $00, $3F, $83, $F0, $00,
    $1F, $83, $F0, $00, $1F, $83, $E0, $00,
    $0F, $C7, $E0, $00, $07, $FF, $C0, $00,
    $07, $FF, $C0, $00, $01, $FF, $80, $00,
    $00, $FF, $00, $00, $00, $3C, $00, $00,
    $00, $00, $00, $00, $00, $00, $00, $00

then create the cursor

hCur := CreateCursor(HInstance, 19, 2, 32, 32, @ANDmaskCursor, @XORmaskCursor);
For an example see the attached sample.

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