Android Open Source - GestureViews State

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Back to project page GestureViews.

License

The source code is released under:

Apache License

Java Source Code

package com.alexvasilkov.gestures;
/* w ww. j  av  a 2  s . c  om*/
import android.graphics.Matrix;

/**
 * Represents 2d transformation state
 */
public class State {

    public static final float COMPARISON_EPSILON = 0.0001f;

    private final Matrix matrix = new Matrix();
    private final float[] tmp = new float[9];

    private float x, y;
    private float zoom = 1f;
    private float rotation;

    public float getX() {
        return x;
    }

    public float getY() {
        return y;
    }

    public float getZoom() {
        return zoom;
    }

    public float getRotation() {
        return rotation;
    }

    /**
     * Applying state to provided matrix. Matrix will contain translation, scale and rotation.
     */
    public void get(Matrix matrix) {
        matrix.set(this.matrix);
    }

    public void translateBy(float dx, float dy) {
        matrix.postTranslate(dx, dy);
        updateFromMatrix(false, false); // only translation is changed
    }

    public void translateTo(float x, float y) {
        matrix.postTranslate(-this.x + x, -this.y + y);
        updateFromMatrix(false, false); // only translation is changed
    }

    public void zoomBy(float factor, float pivotX, float pivotY) {
        matrix.postScale(factor, factor, pivotX, pivotY);
        updateFromMatrix(true, false); // zoom & translation are changed
    }

    public void zoomTo(float zoom, float pivotX, float pivotY) {
        matrix.postScale(zoom / this.zoom, zoom / this.zoom, pivotX, pivotY);
        updateFromMatrix(true, false); // zoom & translation are changed
    }

    public void rotateBy(float angle, float pivotX, float pivotY) {
        matrix.postRotate(angle, pivotX, pivotY);
        updateFromMatrix(false, true); // rotation & translation are changed
    }

    public void rotateTo(float angle, float pivotX, float pivotY) {
        matrix.postRotate(-rotation + angle, pivotX, pivotY);
        updateFromMatrix(false, true); // rotation & translation are changed
    }

    public void set(float x, float y, float zoom, float rotation) {
        this.x = x;
        this.y = y;
        this.zoom = zoom;
        this.rotation = rotation;

        // Note, that order is vital here
        matrix.reset();
        matrix.postScale(zoom, zoom);
        matrix.postRotate(rotation);
        matrix.postTranslate(x, y);
    }

    /**
     * Applying state from given matrix. Matrix should contain correct translation / scale / rotation.
     */
    public void set(Matrix matrix) {
        this.matrix.set(matrix);
        updateFromMatrix(true, true);
    }

    public void set(State other) {
        x = other.x;
        y = other.y;
        zoom = other.zoom;
        rotation = other.rotation;
        matrix.set(other.matrix);
    }

    public State copy() {
        State copy = new State();
        copy.set(this);
        return copy;
    }

    /**
     * Applying state from current matrix.
     * <p/>
     * Having matrix:
     * <pre>
     *     | a  b  tx |
     * A = | c  d  ty |
     *     | 0  0  1  |
     *
     * x = tx
     * y = ty
     * scale = sqrt(b^2+d^2)
     * rotation = atan(c/d) = atan(-b/a)
     * </pre>
     * See <a href="http://stackoverflow.com/questions/4361242/extract-rotation-scale-values-from-2d-transformation-matrix">here</a>.
     */
    private void updateFromMatrix(boolean updateZoom, boolean updateRotation) {
        matrix.getValues(tmp);
        x = tmp[2];
        y = tmp[5];
        if (updateZoom) zoom = (float) Math.sqrt(tmp[1] * tmp[1] + tmp[4] * tmp[4]);
        if (updateRotation) rotation = (float) Math.toDegrees(Math.atan2(tmp[3], tmp[4]));
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        State state = (State) o;

        return equals(state.x, x) && equals(state.y, y) && equals(state.zoom, zoom) && equals(state.rotation, rotation);
    }

    @Override
    public int hashCode() {
        int result = (x != +0.0f ? Float.floatToIntBits(x) : 0);
        result = 31 * result + (y != +0.0f ? Float.floatToIntBits(y) : 0);
        result = 31 * result + (zoom != +0.0f ? Float.floatToIntBits(zoom) : 0);
        result = 31 * result + (rotation != +0.0f ? Float.floatToIntBits(rotation) : 0);
        return result;
    }

    public static boolean equals(float v1, float v2) {
        return Math.abs(v1 - v2) < COMPARISON_EPSILON;
    }

}

Java Source Code List

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