Java tutorial
/* * Copyright (C) 2006 The Android Open Source Project * * 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 android.graphics; import java.io.PrintWriter; import android.os.Parcel; import android.os.Parcelable; import com.android.internal.util.FastMath; /** * RectF holds four float coordinates for a rectangle. The rectangle is * represented by the coordinates of its 4 edges (left, top, right bottom). * These fields can be accessed directly. Use width() and height() to retrieve * the rectangle's width and height. Note: most methods do not check to see that * the coordinates are sorted correctly (i.e. left <= right and top <= bottom). */ public class RectF implements Parcelable { public float left; public float top; public float right; public float bottom; /** * Create a new empty RectF. All coordinates are initialized to 0. */ public RectF() { } /** * Create a new rectangle with the specified coordinates. Note: no range * checking is performed, so the caller must ensure that left <= right and * top <= bottom. * * @param left The X coordinate of the left side of the rectangle * @param top The Y coordinate of the top of the rectangle * @param right The X coordinate of the right side of the rectangle * @param bottom The Y coordinate of the bottom of the rectangle */ public RectF(float left, float top, float right, float bottom) { this.left = left; this.top = top; this.right = right; this.bottom = bottom; } /** * Create a new rectangle, initialized with the values in the specified * rectangle (which is left unmodified). * * @param r The rectangle whose coordinates are copied into the new * rectangle. */ public RectF(RectF r) { if (r == null) { left = top = right = bottom = 0.0f; } else { left = r.left; top = r.top; right = r.right; bottom = r.bottom; } } public RectF(Rect r) { if (r == null) { left = top = right = bottom = 0.0f; } else { left = r.left; top = r.top; right = r.right; bottom = r.bottom; } } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; RectF r = (RectF) o; return left == r.left && top == r.top && right == r.right && bottom == r.bottom; } @Override public int hashCode() { int result = (left != +0.0f ? Float.floatToIntBits(left) : 0); result = 31 * result + (top != +0.0f ? Float.floatToIntBits(top) : 0); result = 31 * result + (right != +0.0f ? Float.floatToIntBits(right) : 0); result = 31 * result + (bottom != +0.0f ? Float.floatToIntBits(bottom) : 0); return result; } public String toString() { return "RectF(" + left + ", " + top + ", " + right + ", " + bottom + ")"; } /** * Return a string representation of the rectangle in a compact form. */ public String toShortString() { return toShortString(new StringBuilder(32)); } /** * Return a string representation of the rectangle in a compact form. * @hide */ public String toShortString(StringBuilder sb) { sb.setLength(0); sb.append('['); sb.append(left); sb.append(','); sb.append(top); sb.append("]["); sb.append(right); sb.append(','); sb.append(bottom); sb.append(']'); return sb.toString(); } /** * Print short representation to given writer. * @hide */ public void printShortString(PrintWriter pw) { pw.print('['); pw.print(left); pw.print(','); pw.print(top); pw.print("]["); pw.print(right); pw.print(','); pw.print(bottom); pw.print(']'); } /** * Returns true if the rectangle is empty (left >= right or top >= bottom) */ public final boolean isEmpty() { return left >= right || top >= bottom; } /** * @return the rectangle's width. This does not check for a valid rectangle * (i.e. left <= right) so the result may be negative. */ public final float width() { return right - left; } /** * @return the rectangle's height. This does not check for a valid rectangle * (i.e. top <= bottom) so the result may be negative. */ public final float height() { return bottom - top; } /** * @return the horizontal center of the rectangle. This does not check for * a valid rectangle (i.e. left <= right) */ public final float centerX() { return (left + right) * 0.5f; } /** * @return the vertical center of the rectangle. This does not check for * a valid rectangle (i.e. top <= bottom) */ public final float centerY() { return (top + bottom) * 0.5f; } /** * Set the rectangle to (0,0,0,0) */ public void setEmpty() { left = right = top = bottom = 0; } /** * Set the rectangle's coordinates to the specified values. Note: no range * checking is performed, so it is up to the caller to ensure that * left <= right and top <= bottom. * * @param left The X coordinate of the left side of the rectangle * @param top The Y coordinate of the top of the rectangle * @param right The X coordinate of the right side of the rectangle * @param bottom The Y coordinate of the bottom of the rectangle */ public void set(float left, float top, float right, float bottom) { this.left = left; this.top = top; this.right = right; this.bottom = bottom; } /** * Copy the coordinates from src into this rectangle. * * @param src The rectangle whose coordinates are copied into this * rectangle. */ public void set(RectF src) { this.left = src.left; this.top = src.top; this.right = src.right; this.bottom = src.bottom; } /** * Copy the coordinates from src into this rectangle. * * @param src The rectangle whose coordinates are copied into this * rectangle. */ public void set(Rect src) { this.left = src.left; this.top = src.top; this.right = src.right; this.bottom = src.bottom; } /** * Offset the rectangle by adding dx to its left and right coordinates, and * adding dy to its top and bottom coordinates. * * @param dx The amount to add to the rectangle's left and right coordinates * @param dy The amount to add to the rectangle's top and bottom coordinates */ public void offset(float dx, float dy) { left += dx; top += dy; right += dx; bottom += dy; } /** * Offset the rectangle to a specific (left, top) position, * keeping its width and height the same. * * @param newLeft The new "left" coordinate for the rectangle * @param newTop The new "top" coordinate for the rectangle */ public void offsetTo(float newLeft, float newTop) { right += newLeft - left; bottom += newTop - top; left = newLeft; top = newTop; } /** * Inset the rectangle by (dx,dy). If dx is positive, then the sides are * moved inwards, making the rectangle narrower. If dx is negative, then the * sides are moved outwards, making the rectangle wider. The same holds true * for dy and the top and bottom. * * @param dx The amount to add(subtract) from the rectangle's left(right) * @param dy The amount to add(subtract) from the rectangle's top(bottom) */ public void inset(float dx, float dy) { left += dx; top += dy; right -= dx; bottom -= dy; } /** * Returns true if (x,y) is inside the rectangle. The left and top are * considered to be inside, while the right and bottom are not. This means * that for a x,y to be contained: left <= x < right and top <= y < bottom. * An empty rectangle never contains any point. * * @param x The X coordinate of the point being tested for containment * @param y The Y coordinate of the point being tested for containment * @return true iff (x,y) are contained by the rectangle, where containment * means left <= x < right and top <= y < bottom */ public boolean contains(float x, float y) { return left < right && top < bottom // check for empty first && x >= left && x < right && y >= top && y < bottom; } /** * Returns true iff the 4 specified sides of a rectangle are inside or equal * to this rectangle. i.e. is this rectangle a superset of the specified * rectangle. An empty rectangle never contains another rectangle. * * @param left The left side of the rectangle being tested for containment * @param top The top of the rectangle being tested for containment * @param right The right side of the rectangle being tested for containment * @param bottom The bottom of the rectangle being tested for containment * @return true iff the the 4 specified sides of a rectangle are inside or * equal to this rectangle */ public boolean contains(float left, float top, float right, float bottom) { // check for empty first return this.left < this.right && this.top < this.bottom // now check for containment && this.left <= left && this.top <= top && this.right >= right && this.bottom >= bottom; } /** * Returns true iff the specified rectangle r is inside or equal to this * rectangle. An empty rectangle never contains another rectangle. * * @param r The rectangle being tested for containment. * @return true iff the specified rectangle r is inside or equal to this * rectangle */ public boolean contains(RectF r) { // check for empty first return this.left < this.right && this.top < this.bottom // now check for containment && left <= r.left && top <= r.top && right >= r.right && bottom >= r.bottom; } /** * If the rectangle specified by left,top,right,bottom intersects this * rectangle, return true and set this rectangle to that intersection, * otherwise return false and do not change this rectangle. No check is * performed to see if either rectangle is empty. Note: To just test for * intersection, use intersects() * * @param left The left side of the rectangle being intersected with this * rectangle * @param top The top of the rectangle being intersected with this rectangle * @param right The right side of the rectangle being intersected with this * rectangle. * @param bottom The bottom of the rectangle being intersected with this * rectangle. * @return true if the specified rectangle and this rectangle intersect * (and this rectangle is then set to that intersection) else * return false and do not change this rectangle. */ public boolean intersect(float left, float top, float right, float bottom) { if (this.left < right && left < this.right && this.top < bottom && top < this.bottom) { if (this.left < left) { this.left = left; } if (this.top < top) { this.top = top; } if (this.right > right) { this.right = right; } if (this.bottom > bottom) { this.bottom = bottom; } return true; } return false; } /** * If the specified rectangle intersects this rectangle, return true and set * this rectangle to that intersection, otherwise return false and do not * change this rectangle. No check is performed to see if either rectangle * is empty. To just test for intersection, use intersects() * * @param r The rectangle being intersected with this rectangle. * @return true if the specified rectangle and this rectangle intersect * (and this rectangle is then set to that intersection) else * return false and do not change this rectangle. */ public boolean intersect(RectF r) { return intersect(r.left, r.top, r.right, r.bottom); } /** * If rectangles a and b intersect, return true and set this rectangle to * that intersection, otherwise return false and do not change this * rectangle. No check is performed to see if either rectangle is empty. * To just test for intersection, use intersects() * * @param a The first rectangle being intersected with * @param b The second rectangle being intersected with * @return true iff the two specified rectangles intersect. If they do, set * this rectangle to that intersection. If they do not, return * false and do not change this rectangle. */ public boolean setIntersect(RectF a, RectF b) { if (a.left < b.right && b.left < a.right && a.top < b.bottom && b.top < a.bottom) { left = Math.max(a.left, b.left); top = Math.max(a.top, b.top); right = Math.min(a.right, b.right); bottom = Math.min(a.bottom, b.bottom); return true; } return false; } /** * Returns true if this rectangle intersects the specified rectangle. * In no event is this rectangle modified. No check is performed to see * if either rectangle is empty. To record the intersection, use intersect() * or setIntersect(). * * @param left The left side of the rectangle being tested for intersection * @param top The top of the rectangle being tested for intersection * @param right The right side of the rectangle being tested for * intersection * @param bottom The bottom of the rectangle being tested for intersection * @return true iff the specified rectangle intersects this rectangle. In * no event is this rectangle modified. */ public boolean intersects(float left, float top, float right, float bottom) { return this.left < right && left < this.right && this.top < bottom && top < this.bottom; } /** * Returns true iff the two specified rectangles intersect. In no event are * either of the rectangles modified. To record the intersection, * use intersect() or setIntersect(). * * @param a The first rectangle being tested for intersection * @param b The second rectangle being tested for intersection * @return true iff the two specified rectangles intersect. In no event are * either of the rectangles modified. */ public static boolean intersects(RectF a, RectF b) { return a.left < b.right && b.left < a.right && a.top < b.bottom && b.top < a.bottom; } /** * Set the dst integer Rect by rounding this rectangle's coordinates * to their nearest integer values. */ public void round(Rect dst) { dst.set(FastMath.round(left), FastMath.round(top), FastMath.round(right), FastMath.round(bottom)); } /** * Set the dst integer Rect by rounding "out" this rectangle, choosing the * floor of top and left, and the ceiling of right and bottom. */ public void roundOut(Rect dst) { dst.set((int) Math.floor(left), (int) Math.floor(top), (int) Math.ceil(right), (int) Math.ceil(bottom)); } /** * Update this Rect to enclose itself and the specified rectangle. If the * specified rectangle is empty, nothing is done. If this rectangle is empty * it is set to the specified rectangle. * * @param left The left edge being unioned with this rectangle * @param top The top edge being unioned with this rectangle * @param right The right edge being unioned with this rectangle * @param bottom The bottom edge being unioned with this rectangle */ public void union(float left, float top, float right, float bottom) { if ((left < right) && (top < bottom)) { if ((this.left < this.right) && (this.top < this.bottom)) { if (this.left > left) this.left = left; if (this.top > top) this.top = top; if (this.right < right) this.right = right; if (this.bottom < bottom) this.bottom = bottom; } else { this.left = left; this.top = top; this.right = right; this.bottom = bottom; } } } /** * Update this Rect to enclose itself and the specified rectangle. If the * specified rectangle is empty, nothing is done. If this rectangle is empty * it is set to the specified rectangle. * * @param r The rectangle being unioned with this rectangle */ public void union(RectF r) { union(r.left, r.top, r.right, r.bottom); } /** * Update this Rect to enclose itself and the [x,y] coordinate. There is no * check to see that this rectangle is non-empty. * * @param x The x coordinate of the point to add to the rectangle * @param y The y coordinate of the point to add to the rectangle */ public void union(float x, float y) { if (x < left) { left = x; } else if (x > right) { right = x; } if (y < top) { top = y; } else if (y > bottom) { bottom = y; } } /** * Swap top/bottom or left/right if there are flipped (i.e. left > right * and/or top > bottom). This can be called if * the edges are computed separately, and may have crossed over each other. * If the edges are already correct (i.e. left <= right and top <= bottom) * then nothing is done. */ public void sort() { if (left > right) { float temp = left; left = right; right = temp; } if (top > bottom) { float temp = top; top = bottom; bottom = temp; } } /** * Parcelable interface methods */ public int describeContents() { return 0; } /** * Write this rectangle to the specified parcel. To restore a rectangle from * a parcel, use readFromParcel() * @param out The parcel to write the rectangle's coordinates into */ public void writeToParcel(Parcel out, int flags) { out.writeFloat(left); out.writeFloat(top); out.writeFloat(right); out.writeFloat(bottom); } public static final Parcelable.Creator<RectF> CREATOR = new Parcelable.Creator<RectF>() { /** * Return a new rectangle from the data in the specified parcel. */ public RectF createFromParcel(Parcel in) { RectF r = new RectF(); r.readFromParcel(in); return r; } /** * Return an array of rectangles of the specified size. */ public RectF[] newArray(int size) { return new RectF[size]; } }; /** * Set the rectangle's coordinates from the data stored in the specified * parcel. To write a rectangle to a parcel, call writeToParcel(). * * @param in The parcel to read the rectangle's coordinates from */ public void readFromParcel(Parcel in) { left = in.readFloat(); top = in.readFloat(); right = in.readFloat(); bottom = in.readFloat(); } /** * Scales up the rect by the given scale. * @hide */ public void scale(float scale) { if (scale != 1.0f) { left = left * scale; top = top * scale; right = right * scale; bottom = bottom * scale; } } }