Create an affine transform given two rectangles. Or, alternatively, two points in the old basis and two corresponding points in the new one. - Java 2D Graphics

Java examples for 2D Graphics:Rectangle

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Description

Create an affine transform given two rectangles. Or, alternatively, two points in the old basis and two corresponding points in the new one.

Demo Code

/* //from   w ww  .j a  v  a2  s.c  o  m
 * Copyright 2016 Dmitry Avtonomov.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
//package com.java2s;
import java.awt.Rectangle;
import java.awt.geom.AffineTransform;

public class Main {
    /**
     * Create an affine transform given two rectangles.<br/>
     * Or, alternatively, two points in the old basis and two corresponding points in the new one.
     * This, obviously, doesn't support rotations.<br/>
     * To transform from [(a,b)-(c,d)] to [(e,f)-(g,h)] perform the following computation:<br/>
     *
     * {@code x' = e + (x - a) * (g - e) / (c - a); } <br/>
     * {@code y' = f + (y - b) * (h - f) / (d - b); } <br/>
     *
     * @param r1 original rectangle
     * @param r2 rectangle we want to transform to
     * @return
     */
    public static AffineTransform transformFromPoints(Rectangle r1,
            Rectangle r2) {
        AffineTransform t = new AffineTransform();
        t.translate(r2.getMinX(), r2.getMinY());
        t.scale(r2.getWidth() / r1.getWidth(),
                r2.getHeight() / r1.getHeight());
        t.translate(-r1.getMinX(), -r1.getMinY());
        return t;
    }
}

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