Add blurhash when available

2 files changed, 142 insertions, 1 deletions

diff --git a/app/src/main/java/app/fedilab/android/mastodon/helper/BlurHashDecoder.kt b/app/src/main/java/app/fedilab/android/mastodon/helper/BlurHashDecoder.kt
new file mode 100644
index 000000000..e192239fa
--- /dev/null
+++ b/app/src/main/java/app/fedilab/android/mastodon/helper/BlurHashDecoder.kt
@@ -0,0 +1,127 @@
+package app.fedilab.android.mastodon.helper
+
+
+import android.graphics.Bitmap
+import android.graphics.Color
+import kotlin.math.PI
+import kotlin.math.cos
+import kotlin.math.pow
+import kotlin.math.withSign
+
+class BlurHashDecoder {
+
+    fun decode(blurHash: String?, width: Int, height: Int, punch: Float = 1f): Bitmap? {
+        require(width > 0) { "Width must be greater than zero" }
+        require(height > 0) { "height must be greater than zero" }
+        if (blurHash == null || blurHash.length < 6) {
+            return null
+        }
+        val numCompEnc = decode83(blurHash, 0, 1)
+        val numCompX = (numCompEnc % 9) + 1
+        val numCompY = (numCompEnc / 9) + 1
+        if (blurHash.length != 4 + 2 * numCompX * numCompY) {
+            return null
+        }
+        val maxAcEnc = decode83(blurHash, 1, 2)
+        val maxAc = (maxAcEnc + 1) / 166f
+        val colors = Array(numCompX * numCompY) { i ->
+            if (i == 0) {
+                val colorEnc = decode83(blurHash, 2, 6)
+                decodeDc(colorEnc)
+            } else {
+                val from = 4 + i * 2
+                val colorEnc = decode83(blurHash, from, from + 2)
+                decodeAc(colorEnc, maxAc * punch)
+            }
+        }
+        return composeBitmap(width, height, numCompX, numCompY, colors)
+    }
+
+    private fun decode83(str: String, from: Int = 0, to: Int = str.length): Int {
+        var result = 0
+        for (i in from until to) {
+            val index = charMap[str[i]] ?: -1
+            if (index != -1) {
+                result = result * 83 + index
+            }
+        }
+        return result
+    }
+
+    private fun decodeDc(colorEnc: Int): FloatArray {
+        val r = colorEnc shr 16
+        val g = (colorEnc shr 8) and 255
+        val b = colorEnc and 255
+        return floatArrayOf(srgbToLinear(r), srgbToLinear(g), srgbToLinear(b))
+    }
+
+    private fun srgbToLinear(colorEnc: Int): Float {
+        val v = colorEnc / 255f
+        return if (v <= 0.04045f) {
+            (v / 12.92f)
+        } else {
+            ((v + 0.055f) / 1.055f).pow(2.4f)
+        }
+    }
+
+    private fun decodeAc(value: Int, maxAc: Float): FloatArray {
+        val r = value / (19 * 19)
+        val g = (value / 19) % 19
+        val b = value % 19
+        return floatArrayOf(
+            signedPow2((r - 9) / 9.0f) * maxAc,
+            signedPow2((g - 9) / 9.0f) * maxAc,
+            signedPow2((b - 9) / 9.0f) * maxAc
+        )
+    }
+
+    private fun signedPow2(value: Float) = value.pow(2f).withSign(value)
+
+    private fun composeBitmap(
+        width: Int,
+        height: Int,
+        numCompX: Int,
+        numCompY: Int,
+        colors: Array<FloatArray>
+    ): Bitmap {
+        val imageArray = IntArray(width * height)
+        for (y in 0 until height) {
+            for (x in 0 until width) {
+                var r = 0f
+                var g = 0f
+                var b = 0f
+                for (j in 0 until numCompY) {
+                    for (i in 0 until numCompX) {
+                        val basis = (cos(PI * x * i / width) * cos(PI * y * j / height)).toFloat()
+                        val color = colors[j * numCompX + i]
+                        r += color[0] * basis
+                        g += color[1] * basis
+                        b += color[2] * basis
+                    }
+                }
+                imageArray[x + width * y] =
+                    Color.rgb(linearToSrgb(r), linearToSrgb(g), linearToSrgb(b))
+            }
+        }
+        return Bitmap.createBitmap(imageArray, width, height, Bitmap.Config.ARGB_8888)
+    }
+
+    private fun linearToSrgb(value: Float): Int {
+        val v = value.coerceIn(0f, 1f)
+        return if (v <= 0.0031308f) {
+            (v * 12.92f * 255f + 0.5f).toInt()
+        } else {
+            ((1.055f * v.pow(1 / 2.4f) - 0.055f) * 255 + 0.5f).toInt()
+        }
+    }
+
+    private val charMap = listOf(
+        '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G',
+        'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
+        'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o',
+        'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '#', '$', '%', '*', '+', ',',
+        '-', '.', ':', ';', '=', '?', '@', '[', ']', '^', '_', '{', '|', '}', '~'
+    )
+        .mapIndexed { i, c -> c to i }
+        .toMap()
+}
\ No newline at end of file
diff --git a/app/src/main/java/app/fedilab/android/mastodon/ui/drawer/StatusAdapter.java b/app/src/main/java/app/fedilab/android/mastodon/ui/drawer/StatusAdapter.java
index 1353d368e..7660beca8 100644
--- a/app/src/main/java/app/fedilab/android/mastodon/ui/drawer/StatusAdapter.java
+++ b/app/src/main/java/app/fedilab/android/mastodon/ui/drawer/StatusAdapter.java
@@ -39,8 +39,10 @@ import android.content.Context;
 import android.content.Intent;
 import android.content.SharedPreferences;
 import android.content.res.Configuration;
+import android.graphics.Bitmap;
 import android.graphics.PorterDuff;
 import android.graphics.Typeface;
+import android.graphics.drawable.BitmapDrawable;
 import android.graphics.drawable.Drawable;
 import android.os.Build;
 import android.os.Bundle;
@@ -138,6 +140,7 @@ import app.fedilab.android.mastodon.client.entities.app.StatusCache;
 import app.fedilab.android.mastodon.client.entities.app.StatusDraft;
 import app.fedilab.android.mastodon.client.entities.app.Timeline;
 import app.fedilab.android.mastodon.exception.DBException;
+import app.fedilab.android.mastodon.helper.BlurHashDecoder;
 import app.fedilab.android.mastodon.helper.CrossActionHelper;
 import app.fedilab.android.mastodon.helper.GlideApp;
 import app.fedilab.android.mastodon.helper.GlideFocus;
@@ -2211,13 +2214,24 @@ public class StatusAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder>
         boolean expand_media = sharedpreferences.getBoolean(context.getString(R.string.SET_EXPAND_MEDIA), false);
         RequestBuilder<Drawable> requestBuilder;
         GlideRequests glideRequests = GlideApp.with(context);
+        Bitmap placeholder = null;
+        if (attachment.blurhash != null) {
+            placeholder = new BlurHashDecoder().decode(attachment.blurhash, 32, 32, 1f);
+        }
         if (!isSensitive || expand_media) {
             requestBuilder = glideRequests.asDrawable();
             if (!fullAttachement) {
+                if (placeholder != null) {
+                    requestBuilder = requestBuilder.placeholder(new BitmapDrawable(context.getResources(), placeholder));
+                }
                 requestBuilder = requestBuilder.apply(new RequestOptions().transform(new GlideFocus(focusX, focusY)));
                 requestBuilder = requestBuilder.dontAnimate();
             } else {
-                requestBuilder = requestBuilder.placeholder(R.color.transparent_grey);
+                if (placeholder != null) {
+                    requestBuilder = requestBuilder.placeholder(new BitmapDrawable(context.getResources(), placeholder));
+                } else {
+                    requestBuilder = requestBuilder.placeholder(R.color.transparent_grey);
+                }
                 requestBuilder = requestBuilder.dontAnimate();
                 requestBuilder = requestBuilder.apply(new RequestOptions().override((int) mediaW, (int) mediaH));
                 requestBuilder = requestBuilder.fitCenter();