Get rid of OpenCV dependency (appium#991)

* Get rid of OpenCV dependency * Fix constructor * Fix linter

Author: Mykola Mokhnach

build.gradle

@@ -75,7 +75,6 @@ dependencies {
  compile 'commons-io:commons-io:2.6'
  compile 'org.springframework:spring-context:5.0.5.RELEASE'
  compile 'org.aspectj:aspectjweaver:1.9.1'
- compile 'org.openpnp:opencv:3.2.0-1'
 
  testCompile 'junit:junit:4.12'
  testCompile 'org.hamcrest:hamcrest-library:1.3'

src/main/java/io/appium/java_client/ScreenshotState.java

@@ -16,29 +16,26 @@
 
 package io.appium.java_client;
 
-import static nu.pattern.OpenCV.loadShared;
+import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Optional.ofNullable;
 
-import org.opencv.core.Core;
-import org.opencv.core.CvType;
-import org.opencv.core.Mat;
-import org.opencv.core.Size;
-import org.opencv.imgproc.Imgproc;
-
-import java.awt.AlphaComposite;
-import java.awt.Graphics2D;
 import java.awt.image.BufferedImage;
-import java.awt.image.DataBufferByte;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
 import java.time.Duration;
 import java.time.LocalDateTime;
-import java.util.Optional;
+import java.util.Base64;
 import java.util.function.Function;
 import java.util.function.Supplier;
 
+import javax.imageio.ImageIO;
+
 public class ScreenshotState {
  private static final Duration DEFAULT_INTERVAL_MS = Duration.ofMillis(500);
 
- private Optional<BufferedImage> previousScreenshot = Optional.empty();
- private Supplier<BufferedImage> stateProvider;
+ private BufferedImage previousScreenshot;
+ private final Supplier<BufferedImage> stateProvider;
+ private final ComparesImages comparator;
 
  private Duration comparisonInterval = DEFAULT_INTERVAL_MS;
 
@@ -72,10 +69,15 @@ public class ScreenshotState {
  *
  * @param stateProvider lambda function, which returns a screenshot for further comparison
  */
- public ScreenshotState(Supplier<BufferedImage> stateProvider) {
+ public ScreenshotState(ComparesImages comparator, Supplier<BufferedImage> stateProvider) {
+ this.comparator = checkNotNull(comparator);
  this.stateProvider = stateProvider;
  }
 
+ public ScreenshotState(ComparesImages comparator) {
+ this(comparator, null);
+ }
+
  /**
  * Gets the interval value in ms between similarity verification rounds in <em>verify*</em> methods.
  *
@@ -103,7 +105,7 @@ public ScreenshotState setComparisonInterval(Duration comparisonInterval) {
  * @return self instance for chaining
  */
  public ScreenshotState remember() {
- this.previousScreenshot = Optional.of(stateProvider.get());
+ this.previousScreenshot = stateProvider.get();
  return this;
  }
 
@@ -116,7 +118,7 @@ public ScreenshotState remember() {
  * @return self instance for chaining
  */
  public ScreenshotState remember(BufferedImage customInitialState) {
- this.previousScreenshot = Optional.of(customInitialState);
+ this.previousScreenshot = checkNotNull(customInitialState);
  return this;
  }
 
@@ -134,7 +136,7 @@ public static class ScreenshotComparisonError extends RuntimeException {
 
  public static class ScreenshotComparisonTimeout extends RuntimeException {
  private static final long serialVersionUID = 6336247721154252476L;
- private double currentScore = Double.NaN;
+ private final double currentScore;
 
  ScreenshotComparisonTimeout(String message, double currentScore) {
  super(message);
@@ -147,17 +149,13 @@ public double getCurrentScore() {
  }
 
  private ScreenshotState checkState(Function<Double, Boolean> checkerFunc, Duration timeout) {
- return checkState(checkerFunc, timeout, ResizeMode.NO_RESIZE);
- }
-
- private ScreenshotState checkState(Function<Double, Boolean> checkerFunc, Duration timeout, ResizeMode resizeMode) {
  final LocalDateTime started = LocalDateTime.now();
  double score;
  do {
  final BufferedImage currentState = stateProvider.get();
- score = getOverlapScore(this.previousScreenshot
+ score = getOverlapScore(ofNullable(this.previousScreenshot)
  .orElseThrow(() -> new ScreenshotComparisonError("Initial screenshot state is not set. "
- + "Nothing to compare")), currentState, resizeMode);
+ + "Nothing to compare")), currentState);
  if (checkerFunc.apply(score)) {
  return this;
  }
@@ -188,25 +186,6 @@ public ScreenshotState verifyChanged(Duration timeout, double minScore) {
  return checkState((x) -> x < minScore, timeout);
  }
 
- /**
- * Verifies whether the state of the screenshot provided by stateProvider lambda function
- * is changed within the given timeout.
- *
- * @param timeout timeout value
- * @param minScore the value in range (0.0, 1.0)
- * @param resizeMode one of <em>ResizeMode</em> enum values.
- * Set it to a value different from <em>NO_RESIZE</em>
- * if the actual screenshot is expected to have different
- * dimensions in comparison to the previously remembered one
- * @return self instance for chaining
- * @throws ScreenshotComparisonTimeout if the calculated score is still
- * greater or equal to the given score after timeout happens
- * @throws ScreenshotComparisonError if {@link #remember()} method has not been invoked yet
- */
- public ScreenshotState verifyChanged(Duration timeout, double minScore, ResizeMode resizeMode) {
- return checkState((x) -> x < minScore, timeout, resizeMode);
- }
-
  /**
  * Verifies whether the state of the screenshot provided by stateProvider lambda function
  * is not changed within the given timeout.
@@ -222,112 +201,28 @@ public ScreenshotState verifyNotChanged(Duration timeout, double minScore) {
  return checkState((x) -> x >= minScore, timeout);
  }
 
- /**
- * Verifies whether the state of the screenshot provided by stateProvider lambda function
- * is changed within the given timeout.
- *
- * @param timeout timeout value
- * @param minScore the value in range (0.0, 1.0)
- * @param resizeMode one of <em>ResizeMode</em> enum values.
- * Set it to a value different from <em>NO_RESIZE</em>
- * if the actual screenshot is expected to have different
- * dimensions in comparison to the previously remembered one
- * @return self instance for chaining
- * @throws ScreenshotComparisonTimeout if the calculated score is still
- * less than the given score after timeout happens
- * @throws ScreenshotComparisonError if {@link #remember()} method has not been invoked yet
- */
- public ScreenshotState verifyNotChanged(Duration timeout, double minScore, ResizeMode resizeMode) {
- return checkState((x) -> x >= minScore, timeout, resizeMode);
- }
-
- private static Mat prepareImageForComparison(BufferedImage srcImage) {
- final BufferedImage normalizedBitmap = new BufferedImage(srcImage.getWidth(), srcImage.getHeight(),
- BufferedImage.TYPE_3BYTE_BGR);
- final Graphics2D g = normalizedBitmap.createGraphics();
- try {
- g.setComposite(AlphaComposite.Src);
- g.drawImage(srcImage, 0, 0, null);
- } finally {
- g.dispose();
- }
- final byte[] pixels = ((DataBufferByte) normalizedBitmap.getRaster().getDataBuffer()).getData();
- final Mat result = new Mat(normalizedBitmap.getHeight(), normalizedBitmap.getWidth(), CvType.CV_8UC3);
- result.put(0, 0, pixels);
- return result;
- }
-
- private static Mat resizeFirstMatrixToSecondMatrixResolution(Mat first, Mat second) {
- if (first.width() != second.width() || first.height() != second.height()) {
- final Mat result = new Mat();
- final Size sz = new Size(second.width(), second.height());
- Imgproc.resize(first, result, sz);
- return result;
- }
- return first;
- }
-
- /**
- * A shortcut to {@link #getOverlapScore(BufferedImage, BufferedImage, ResizeMode)} method
- * for the case if both reference and template images are expected to have the same dimensions.
- *
- * @param refImage reference image
- * @param tplImage template
- * @return similarity score value in range (-1.0, 1.0). 1.0 is returned if the images are equal
- * @throws ScreenshotComparisonError if provided images are not valid or have different resolution
- */
- public static double getOverlapScore(BufferedImage refImage, BufferedImage tplImage) {
- return getOverlapScore(refImage, tplImage, ResizeMode.NO_RESIZE);
- }
-
  /**
  * Compares two valid java bitmaps and calculates similarity score between them.
+ * Both images are expected to be of the same size/resolution. The method
+ * implicitly invokes {@link ComparesImages#getImagesSimilarity(byte[], byte[])}.
  *
  * @param refImage reference image
  * @param tplImage template
- * @param resizeMode one of possible enum values. Set it either to <em>TEMPLATE_TO_REFERENCE_RESOLUTION</em> or
- * <em>REFERENCE_TO_TEMPLATE_RESOLUTION</em> if given bitmaps have different dimensions
- * @return similarity score value in range (-1.0, 1.0). 1.0 is returned if the images are equal
+ * @return similarity score value in range (-1.0, 1.0]. 1.0 is returned if the images are equal
  * @throws ScreenshotComparisonError if provided images are not valid or have
- * different resolution, but resizeMode has been set to <em>NO_RESIZE</em>
+ * different resolution
  */
- public static double getOverlapScore(BufferedImage refImage, BufferedImage tplImage, ResizeMode resizeMode) {
- Mat ref = prepareImageForComparison(refImage);
- if (ref.empty()) {
- throw new ScreenshotComparisonError("Reference image cannot be converted for further comparison");
- }
- Mat tpl = prepareImageForComparison(tplImage);
- if (tpl.empty()) {
- throw new ScreenshotComparisonError("Template image cannot be converted for further comparison");
- }
- switch (resizeMode) {
- case TEMPLATE_TO_REFERENCE_RESOLUTION:
- tpl = resizeFirstMatrixToSecondMatrixResolution(tpl, ref);
- break;
- case REFERENCE_TO_TEMPLATE_RESOLUTION:
- ref = resizeFirstMatrixToSecondMatrixResolution(ref, tpl);
- break;
- default:
- // do nothing
- }
-
- if (ref.width() != tpl.width() || ref.height() != tpl.height()) {
- throw new ScreenshotComparisonError(
- "Resolutions of template and reference images are expected to be equal. "
- + "Try different resizeMode value."
- );
+ public double getOverlapScore(BufferedImage refImage, BufferedImage tplImage) {
+ try (ByteArrayOutputStream img1 = new ByteArrayOutputStream();
+ ByteArrayOutputStream img2 = new ByteArrayOutputStream()) {
+ ImageIO.write(refImage, "png", img1);
+ ImageIO.write(tplImage, "png", img2);
+ return comparator
+ .getImagesSimilarity(Base64.getEncoder().encode(img1.toByteArray()),
+ Base64.getEncoder().encode(img2.toByteArray()))
+ .getScore();
+ } catch (IOException e) {
+ throw new ScreenshotComparisonError(e);
  }
-
- Mat res = new Mat(ref.rows() - tpl.rows() + 1, ref.cols() - tpl.cols() + 1, CvType.CV_32FC1);
- Imgproc.matchTemplate(ref, tpl, res, Imgproc.TM_CCOEFF_NORMED);
- return Core.minMaxLoc(res).maxVal;
- }
-
- public enum ResizeMode {
- NO_RESIZE, TEMPLATE_TO_REFERENCE_RESOLUTION, REFERENCE_TO_TEMPLATE_RESOLUTION
- }
-
- static {
- loadShared();
  }
 }