To Next Page

To Previous Page

Capture and Release of the Pointer

When an object gains focus, it also gains focus of the pointer. Once you gain focus of the

pointer you may wish to continue to receive events based on the pointer even if your

object no longer has focus. The following two functions allow you to accomplish this:

void CapturePointer(void);

void ReleasePointer(void);

These functions can be useful when dragging an object on the screen. You could, for

example, call CapturePointer() on pen down and ReleasePointer() on pen up of a

certain object. In this case, even if the pen leaves this object’s boundaries (and goes into

a different module window, for example) the pointer messages will continue to go to the

object. When the user lifts up the pen, the pointer will be released and the object will no

longer own the pointer. Be extremely careful that when you do capture the pointer that

you are certain to release it. Otherwise user input will be stuck on the object that

captured and didn’t release the pointer.

PEG Data Types

In section we will look at some important data types that are used in PEG and throughout

the ClassPad, but are not based on the PegThing.

Fundamental Data Types

The following simple data types are used by PEG instead of the intrinsic data types

defined by the compiler to avoid conflicts when running on CPUs with differing basic

word length and data manipulation capabilities. The comment next to each data type

describes the storage requirements PEG requires for each type:

typedef char CHAR // 8 bit signed

typedef unsigned char UCHAR // 8 bit unsigned

typedef short SIGNED // 16 bit signed

typedef unsigned short WORD // 16 bit unsigned

typedef int LONG // 32 bit signed

typedef unsigned int DWORD // 32 bit unsigned

PegPoint

PegPoint is a basic pixel address data type. The x,y position is always relative to the top-

left corner of the screen. PegPoint is defined as:

struct PegPoint

{

SIGNED x;

SIGNED y;

};

Note that PegPoint contains SIGNED data values. This means that it is perfectly normal

and acceptable during the operation of PEG for at least some portion of an object to have

Casio ClassPad 300 Programming Guide

Other manuals for Casio ClassPad 300