Custom Clipper in Flutter

In this tutorial we will see how to we can make a custom clipper with straight lines in Flutter. Custom clipper can be used to clip the widget into any desired shape.

Source Code

The entire code for clipping a widget in a triangle is shown in the above source code. The step by step instruction for how to create the custom clipper will be explained below.

Steps

Step 0 – The first thing you have to keep in mind while defining a custom clipper is that in Flutter X axis is positive in right direction and negative in left direction as normal cartesian co-ordinate system. But, the Y axis is positive downward direction and negative in the upward direction.

Step 1 – Clipping always starts from (0, 0) which is the top-left corner of the widget. But in our case we need to start at top center point(width/2, 0). In the code shown below, we move to point (width/2, 0) without cliiping.

Step 2 – In step 2, we start the clipping motion from top center where the marker is now to bottom right corner (width, height). Keep in mind that in flutter Y axis is positive in the downward direction.

Step 3 – In step 3, the clipping motion is from bottom right corner to bottom left corner (0, height).

Step 4 – In the final step, we close the clipping to clip the widget into a triangle.