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Display Line Animation on a Form Sample

  • Artículo

File: ...\Samples\Solution\Forms\Graphics\Anim.scx

This sample illustrates drawing lines on a form. More specifically, it demonstrates saving coordinates of sets of lines drawn on a form and redrawing them, along with additional lines at intermediate positions, giving the illusion of motion.

Adding Lines to the Table

Each time a user draws a line on the form, its coordinates are stored in a table with the following structure:

Name

Type

Description

Frameno

I

Incremented each time the user chooses New Frame.

Objno

I

Incremented each time a line is added to a frame.

X1

I

The starting X coordinate for a line.

X2

I

The ending X coordinate for a line.

Y1

I

The starting Y coordinate for a line

Y2

I

The ending Y coordinate for a line.

Playing the Frames

The following code plays the frames, uses the table again in another work area, selects the second work area, and goes to the next frame:

USE (lcTable) AGAIN IN 0 ALIAS shadow
SELECT shadow
LOCATE FOR frameno # &lcTable..frameno

The variable nBetween determines how many intermediate lines are drawn on the form between a line in one frame and the corresponding line in the next frame.

FOR nb = 1 TO nBetween

Inside the FOR loop, the code scans for all of the lines associated with a frame and calculates coordinates for the intermediate lines, for example:

nx1 = frames.x1 + nb * (shadow.x1 - frames.x1) / nBetween
ny1 = frames.y1 + nb * (shadow.y1 - frames.y1) / nBetween

The code then prints each intermediate line, and after a WAIT of .05 seconds clears the form and continues the loop.

THISFORMSET.frmAnimation.line(nx1,ny1,nx2,ny2)

See Also

Tasks

Draw Lines and Shapes on a Form Sample

Solution Samples

Reference

Visual FoxPro Foundation Classes A-Z

Other Resources

Forms Solution Samples