Improve explore fragment

app/src/main/java/org/koitharu/kotatsu/utils/image/FaviconFallbackDrawable.kt

@@ -0,0 +1,66 @@
+package org.koitharu.kotatsu.utils.image
+
+import android.content.Context
+import android.graphics.*
+import android.graphics.drawable.Drawable
+import androidx.core.graphics.ColorUtils
+import kotlin.math.absoluteValue
+
+class FaviconFallbackDrawable(
+	context: Context,
+	name: String,
+) : Drawable() {
+
+	private val paint = Paint(Paint.ANTI_ALIAS_FLAG)
+	private val letter = name.take(1).uppercase()
+	private val color = colorOfString(name)
+	private val textBounds = Rect()
+	private val tempRect = Rect()
+
+	init {
+		paint.style = Paint.Style.FILL
+		paint.textAlign = Paint.Align.CENTER
+		paint.isFakeBoldText = true
+	}
+
+	override fun draw(canvas: Canvas) {
+		val cx = bounds.exactCenterX()
+		paint.color = color
+		canvas.drawPaint(paint)
+		paint.color = Color.WHITE
+		val ty = bounds.height() / 2f + textBounds.height() / 2f - textBounds.bottom
+		canvas.drawText(letter, cx, ty, paint)
+	}
+
+	override fun onBoundsChange(bounds: Rect) {
+		super.onBoundsChange(bounds)
+		val innerWidth = bounds.width() - (paint.strokeWidth * 2f)
+		paint.textSize = getTextSizeForWidth(innerWidth, "100%")
+		paint.getTextBounds(letter, 0, letter.length, textBounds)
+		invalidateSelf()
+	}
+
+	override fun setAlpha(alpha: Int) {
+		paint.alpha = alpha
+	}
+
+	override fun setColorFilter(colorFilter: ColorFilter?) {
+		paint.colorFilter = colorFilter
+	}
+
+	@Suppress("DeprecatedCallableAddReplaceWith")
+	@Deprecated("Deprecated in Java")
+	override fun getOpacity() = PixelFormat.TRANSPARENT
+
+	private fun getTextSizeForWidth(width: Float, text: String): Float {
+		val testTextSize = 48f
+		paint.textSize = testTextSize
+		paint.getTextBounds(text, 0, text.length, tempRect)
+		return testTextSize * width / tempRect.width()
+	}
+
+	private fun colorOfString(str: String): Int {
+		val hue = (str.hashCode() % 360).absoluteValue.toFloat()
+		return ColorUtils.HSLToColor(floatArrayOf(hue, 0.5f, 0.5f))
+	}
+}