On some versions of Android, precise scaling is not possible. In those cases, the strategies + * can only pick between downsampling to between 1x the requested size and 2x the requested size and + * between 0.5x the requested size and 1x the requested size because only power of two downsampling + * is supported. To preserve the potential for a {@link com.bumptech.glide.load.Transformation} to + * scale precisely without a loss in quality, all but {@link #AT_MOST} will prefer to downsample to + * between 1x and 2x the requested size. */ // Public API. @SuppressWarnings("WeakerAccess") public abstract class DownsampleStrategy { + /** + * Downsamples so the image's smallest dimension is between the given dimensions and 2x the given + * dimensions, with no size restrictions on the image's largest dimension. + * + *
Does not upscale if the requested dimensions are larger than the original dimensions. + */ + public static final DownsampleStrategy AT_LEAST = new AtLeast(); + + /** + * Downsamples so the image's largest dimension is between 1/2 the given dimensions and the given + * dimensions, with no restrictions on the image's smallest dimension. + * + *
Does not upscale if the requested dimensions are larger than the original dimensions. + */ + public static final DownsampleStrategy AT_MOST = new AtMost(); + /** * Scales, maintaining the original aspect ratio, so that one of the image's dimensions is exactly * equal to the requested size and the other dimension is less than or equal to the requested @@ -31,11 +55,17 @@ public abstract class DownsampleStrategy { * and height. To avoid upscaling, use {@link #AT_LEAST}, {@link #AT_MOST} or {@link * #CENTER_INSIDE}. * - *
On pre-KitKat devices, {@link Downsampler} treats this as equivalent to {@link #AT_MOST} - * because only power of two downsampling can be used. + *
On pre-KitKat devices, {@code FIT_CENTER} will downsample by a power of two only so that one + * of the image's dimensions is greater than or equal to the requested size. No guarantees are + * made about the second dimensions. This is NOT the same as {@link #AT_LEAST} because + * only one dimension, not both, are greater than or equal to the requested dimensions, the other + * may be smaller. */ public static final DownsampleStrategy FIT_CENTER = new FitCenter(); + /** Identical to {@link #FIT_CENTER}, but never upscales. */ + public static final DownsampleStrategy CENTER_INSIDE = new CenterInside(); + /** * Scales, maintaining the original aspect ratio, so that one of the image's dimensions is exactly * equal to the requested size and the other dimension is greater than or equal to the requested @@ -50,31 +80,6 @@ public abstract class DownsampleStrategy { */ public static final DownsampleStrategy CENTER_OUTSIDE = new CenterOutside(); - /** - * Downsamples so the image's smallest dimension is between the given dimensions and 2x the given - * dimensions, with no size restrictions on the image's largest dimension. - * - *
Does not upscale if the requested dimensions are larger than the original dimensions. - */ - public static final DownsampleStrategy AT_LEAST = new AtLeast(); - - /** - * Downsamples so the image's largest dimension is between 1/2 the given dimensions and the given - * dimensions, with no restrictions on the image's smallest dimension. - * - *
Does not upscale if the requested dimensions are larger than the original dimensions. - */ - public static final DownsampleStrategy AT_MOST = new AtMost(); - - /** - * Returns the original image if it is smaller than the target, otherwise it will be downscaled - * maintaining its original aspect ratio, so that one of the image's dimensions is exactly equal - * to the requested size and the other is less or equal than the requested size. - * - *
Does not upscale if the requested dimensions are larger than the original dimensions. - */ - public static final DownsampleStrategy CENTER_INSIDE = new CenterInside(); - /** Performs no downsampling or scaling. */ public static final DownsampleStrategy NONE = new None(); @@ -92,6 +97,10 @@ public abstract class DownsampleStrategy { Option.memory( "com.bumptech.glide.load.resource.bitmap.Downsampler.DownsampleStrategy", DEFAULT); + @Synthetic + static final boolean IS_BITMAP_FACTORY_SCALING_SUPPORTED = + Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT; + /** * Returns a float (0, +infinity) indicating a scale factor to apply to the source width and * height when displayed in the requested width and height. @@ -133,15 +142,31 @@ private static class FitCenter extends DownsampleStrategy { @Override public float getScaleFactor( int sourceWidth, int sourceHeight, int requestedWidth, int requestedHeight) { - float widthPercentage = requestedWidth / (float) sourceWidth; - float heightPercentage = requestedHeight / (float) sourceHeight; - return Math.min(widthPercentage, heightPercentage); + if (IS_BITMAP_FACTORY_SCALING_SUPPORTED) { + float widthPercentage = requestedWidth / (float) sourceWidth; + float heightPercentage = requestedHeight / (float) sourceHeight; + + return Math.min(widthPercentage, heightPercentage); + } else { + // Similar to AT_LEAST, but only require one dimension or the other to be >= requested + // rather than both. + int maxIntegerFactor = + Math.max(sourceHeight / requestedHeight, sourceWidth / requestedWidth); + return maxIntegerFactor == 0 ? 1f : 1f / Integer.highestOneBit(maxIntegerFactor); + } } @Override public SampleSizeRounding getSampleSizeRounding( int sourceWidth, int sourceHeight, int requestedWidth, int requestedHeight) { - return SampleSizeRounding.QUALITY; + if (IS_BITMAP_FACTORY_SCALING_SUPPORTED) { + return SampleSizeRounding.QUALITY; + } else { + // TODO: This doesn't seem right, but otherwise we can skip a sample size because QUALITY + // prefers the smaller of the the width and height scale factor. MEMORY is a hack that + // lets us prefer the larger of the two. + return SampleSizeRounding.MEMORY; + } } } @@ -246,7 +271,10 @@ public float getScaleFactor( @Override public SampleSizeRounding getSampleSizeRounding( int sourceWidth, int sourceHeight, int requestedWidth, int requestedHeight) { - return SampleSizeRounding.QUALITY; + return getScaleFactor(sourceWidth, sourceHeight, requestedWidth, requestedHeight) == 1.f + ? SampleSizeRounding.QUALITY + : FIT_CENTER.getSampleSizeRounding( + sourceWidth, sourceHeight, requestedWidth, requestedHeight); } } diff --git a/library/src/main/java/com/bumptech/glide/load/resource/bitmap/Downsampler.java b/library/src/main/java/com/bumptech/glide/load/resource/bitmap/Downsampler.java index 9ab9da8ac0..9bf7c51401 100644 --- a/library/src/main/java/com/bumptech/glide/load/resource/bitmap/Downsampler.java +++ b/library/src/main/java/com/bumptech/glide/load/resource/bitmap/Downsampler.java @@ -430,6 +430,9 @@ private static void calculateScaling( int widthScaleFactor = orientedSourceWidth / outWidth; int heightScaleFactor = orientedSourceHeight / outHeight; + // TODO: This isn't really right for both CenterOutside and CenterInside. Consider allowing + // DownsampleStrategy to pick, or trying to do something more sophisticated like picking the + // scale factor that leads to an exact match. int scaleFactor = rounding == SampleSizeRounding.MEMORY ? Math.max(widthScaleFactor, heightScaleFactor) diff --git a/library/test/src/test/java/com/bumptech/glide/load/resource/bitmap/DownsampleStrategyTest.java b/library/test/src/test/java/com/bumptech/glide/load/resource/bitmap/DownsampleStrategyTest.java index 7184c4b66d..74b4b27895 100644 --- a/library/test/src/test/java/com/bumptech/glide/load/resource/bitmap/DownsampleStrategyTest.java +++ b/library/test/src/test/java/com/bumptech/glide/load/resource/bitmap/DownsampleStrategyTest.java @@ -8,7 +8,7 @@ import org.robolectric.annotation.Config; @RunWith(RobolectricTestRunner.class) -@Config(sdk = 18) +@Config(sdk = 21) public class DownsampleStrategyTest { @Test