Window Coordinate System
The coordinate system for a window is based on the coordinate system of the
display device. The basic unit of measure is the device unit (typically, the
pixel). Points on the screen are described by x- and y-coordinate pairs. The
x-coordinates increase to the right; y-coordinates increase from top to bottom. The
origin (0,0) for the system depends on the type of coordinates being used.
Windows and applications specify the position of a window on the screen in
screen coordinates. For screen coordinates, the origin is the upper left corner of the screen.
The full position of a window is often described by a
RECT structure containing the screen coordinates of two points that define the
upper left and lower right corners of the window.
Windows and applications specify the position of points in a window by using
client coordinates. The origin in this case is the upper left corner of the window or client
area. Client coordinates ensure that an application can use consistent coordinate
values while drawing in the window, regardless of the position of the window on
the screen.
The dimensions of the client area are also described by a
RECT structure that contains client coordinates for the area. In all cases, the
upper left coordinate of the rectangle is included in the window or client area,
while the lower right coordinate is excluded. Graphics operations in a window
or client area are excluded from the right and lower edges of the enclosing
rectangle.
Occasionally, applications may be required to map coordinates in one window to
those of another window. An application can map coordinates by using the
MapWindowPoints function. If one of the windows is the desktop window, the function
effectively converts screen coordinates to client coordinates and vice versa; the
desktop window is always specified in screen coordinates.
- Software for developers
-
Delphi Components
.Net Components
Software for Android Developers
- More information resources
-
MegaDetailed.Net
Unix Manual Pages
Delphi Examples
- Databases for Amazon shops developers
-
Amazon Categories Database
Browse Nodes Database
