Using Simulink

Controlling Icon Properties

You can control a masked block's icon properties by selecting among the choices below the Drawing commands field.

Icon frame

The icon frame is the rectangle that encloses the block. You can choose to show or hide the frame by setting the Icon frame parameter to Visible or Invisible. The default is to make the icon frame visible. For example, this figure shows visible and invisible icon frames for an AND gate block.

Icon transparency

The icon can be set to Opaque or Transparent, either hiding or showing what is underneath the icon. Opaque, the default, covers information Simulink draws, such as port labels. This figure shows opaque and transparent icons for an AND gate block. Notice the text on the transparent icon.

Icon rotation

When the block is rotated or flipped, you can choose whether to rotate or flip the icon, or to have it remain fixed in its original orientation. The default is not to rotate the icon. The icon rotation is consistent with block port rotation. This figure shows the results of choosing Fixed and Rotates icon rotation when the AND gate block is rotated.

Drawing coordinates

This parameter controls the coordinate system used by the drawing commands. This parameter applies only to plot and text drawing commands. You can select from among these choices: Autoscale, Normalized, and Pixel.

• Autoscale automatically scales the icon within the block frame. When the block is resized, the icon is also resized. For example, this figure shows the icon drawn using these vectors.

X = [0 2 3 4 9]; Y = [4 6 3 5 8];

The lower-left corner of the block frame is (0,3) and the upper-right corner is (9,8). The range of the x-axis is 9 (from 0 to 9), while the range of the y-axis is 5 (from 3 to 8).

• Normalized draws the icon within a block frame whose bottom-left corner is (0,0) and whose top right corner is (1,1). Only X and Y values between 0 and 1 appear. When the block is resized, the icon is also resized. For example, this figure shows the icon drawn using these vectors.

X = [.0 .2 .3 .4 .9]; Y = [.4 .6 .3 .5 .8];

• Pixel draws the icon with X and Y values expressed in pixels. The icon is not automatically resized when the block is resized. To force the icon to resize with the block, define the drawing commands in terms of the block size.

This example demonstrates how to create an improved icon for the mx + b sample masked subsystem discussed earlier in this chapter. These initialization commands define the data that enables the drawing command to produce an accurate icon regardless of the shape of the block.

pos = get_param(gcb, 'Position');
width = pos(3) - pos(1); height = pos(4) - pos(2);
x = [0, width];
if (m >= 0), y = [0, (m*width)]; end
if (m < 0),  y = [height, (height + (m*width))]; end

The drawing command that generates this icon is plot(x,y).

Displaying a Transfer Function on the Block Icon

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