Color inversion in pages color filter #372

app/src/main/kotlin/org/koitharu/kotatsu/reader/domain/ReaderColorFilter.kt

@@ -6,35 +6,27 @@ import android.graphics.ColorMatrixColorFilter
 class ReaderColorFilter(
 	val brightness: Float,
 	val contrast: Float,
+	val isInverted: Boolean,
 ) {
 
 	val isEmpty: Boolean
-		get() = brightness == 0f && contrast == 0f
+		get() = !isInverted && brightness == 0f && contrast == 0f
 
 	fun toColorFilter(): ColorMatrixColorFilter {
 		val cm = ColorMatrix()
-		val scale = brightness + 1f
-		cm.setScale(scale, scale, scale, 1f)
+		if (isInverted) {
+			cm.inverted()
+		}
+		cm.setBrightness(brightness)
 		cm.setContrast(contrast)
 		return ColorMatrixColorFilter(cm)
 	}
 
-	override fun equals(other: Any?): Boolean {
-		if (this === other) return true
-		if (javaClass != other?.javaClass) return false
-
-		other as ReaderColorFilter
-
-		if (brightness != other.brightness) return false
-		if (contrast != other.contrast) return false
-
-		return true
-	}
-
-	override fun hashCode(): Int {
-		var result = brightness.hashCode()
-		result = 31 * result + contrast.hashCode()
-		return result
+	private fun ColorMatrix.setBrightness(brightness: Float) {
+		val scale = brightness + 1f
+		val matrix = ColorMatrix()
+		matrix.setScale(scale, scale, scale, 1f)
+		postConcat(matrix)
 	}
 
 	private fun ColorMatrix.setContrast(contrast: Float) {
@@ -49,4 +41,32 @@ class ReaderColorFilter(
 		val matrix = ColorMatrix(array)
 		postConcat(matrix)
 	}
+
+	private fun ColorMatrix.inverted() {
+		val matrix = floatArrayOf(
+			-1.0f, 0.0f, 0.0f, 1.0f, 1.0f,
+			0.0f, -1.0f, 0.0f, 1.0f, 1.0f,
+			0.0f, 0.0f, -1.0f, 1.0f, 1.0f,
+			0.0f, 0.0f, 0.0f, 1.0f, 0.0f,
+		)
+		set(matrix)
+	}
+
+	override fun equals(other: Any?): Boolean {
+		if (this === other) return true
+		if (javaClass != other?.javaClass) return false
+
+		other as ReaderColorFilter
+
+		if (brightness != other.brightness) return false
+		if (contrast != other.contrast) return false
+		return isInverted == other.isInverted
+	}
+
+	override fun hashCode(): Int {
+		var result = brightness.hashCode()
+		result = 31 * result + contrast.hashCode()
+		result = 31 * result + isInverted.hashCode()
+		return result
+	}
 }

app/src/main/kotlin/org/koitharu/kotatsu/reader/ui/colorfilter/ColorFilterConfigActivity.kt

@@ -6,6 +6,7 @@ import android.content.res.Resources
 import android.os.Bundle
 import android.view.View
 import android.view.ViewGroup
+import android.widget.CompoundButton
 import androidx.activity.viewModels
 import androidx.core.graphics.Insets
 import androidx.core.view.updateLayoutParams
@@ -26,6 +27,7 @@ import org.koitharu.kotatsu.core.util.ext.enqueueWith
 import org.koitharu.kotatsu.core.util.ext.indicator
 import org.koitharu.kotatsu.core.util.ext.observe
 import org.koitharu.kotatsu.core.util.ext.observeEvent
+import org.koitharu.kotatsu.core.util.ext.setChecked
 import org.koitharu.kotatsu.core.util.ext.setValueRounded
 import org.koitharu.kotatsu.databinding.ActivityColorFilterBinding
 import org.koitharu.kotatsu.parsers.model.Manga
@@ -39,7 +41,7 @@ import com.google.android.material.R as materialR
 class ColorFilterConfigActivity :
 	BaseActivity<ActivityColorFilterBinding>(),
 	Slider.OnChangeListener,
-	View.OnClickListener {
+	View.OnClickListener, CompoundButton.OnCheckedChangeListener {
 
 	@Inject
 	lateinit var coil: ImageLoader
@@ -58,6 +60,7 @@ class ColorFilterConfigActivity :
 		val formatter = PercentLabelFormatter(resources)
 		viewBinding.sliderContrast.setLabelFormatter(formatter)
 		viewBinding.sliderBrightness.setLabelFormatter(formatter)
+		viewBinding.switchInvert.setOnCheckedChangeListener(this)
 		viewBinding.buttonDone.setOnClickListener(this)
 		viewBinding.buttonReset.setOnClickListener(this)
 
@@ -80,6 +83,10 @@ class ColorFilterConfigActivity :
 		}
 	}
 
+	override fun onCheckedChanged(buttonView: CompoundButton?, isChecked: Boolean) {
+		viewModel.setInversion(isChecked)
+	}
+
 	override fun onClick(v: View) {
 		when (v.id) {
 			R.id.button_done -> viewModel.save()
@@ -103,13 +110,14 @@ class ColorFilterConfigActivity :
 	private fun onColorFilterChanged(readerColorFilter: ReaderColorFilter?) {
 		viewBinding.sliderBrightness.setValueRounded(readerColorFilter?.brightness ?: 0f)
 		viewBinding.sliderContrast.setValueRounded(readerColorFilter?.contrast ?: 0f)
+		viewBinding.switchInvert.setChecked(readerColorFilter?.isInverted ?: false, false)
 		viewBinding.imageViewAfter.colorFilter = readerColorFilter?.toColorFilter()
 	}
 
 	private fun onPreviewChanged(preview: MangaPage?) {
 		if (preview == null) return
 		ImageRequest.Builder(this@ColorFilterConfigActivity)
-			.data(preview.url)
+			.data(preview)
 			.scale(Scale.FILL)
 			.decodeRegion()
 			.tag(preview.source)
@@ -117,7 +125,7 @@ class ColorFilterConfigActivity :
 			.error(R.drawable.ic_error_placeholder)
 			.size(ViewSizeResolver(viewBinding.imageViewBefore))
 			.allowRgb565(false)
-			.target(ShadowViewTarget(viewBinding.imageViewBefore, viewBinding.imageViewAfter))
+			.target(DoubleViewTarget(viewBinding.imageViewBefore, viewBinding.imageViewAfter))
 			.enqueueWith(coil)
 	}
 

app/src/main/kotlin/org/koitharu/kotatsu/reader/ui/colorfilter/ColorFilterConfigViewModel.kt

@@ -55,12 +55,32 @@ class ColorFilterConfigViewModel @Inject constructor(
 
 	fun setBrightness(brightness: Float) {
 		val cf = colorFilter.value
-		colorFilter.value = ReaderColorFilter(brightness, cf?.contrast ?: 0f).takeUnless { it.isEmpty }
+		colorFilter.value = ReaderColorFilter(
+			brightness = brightness,
+			contrast = cf?.contrast ?: 0f,
+			isInverted = cf?.isInverted ?: false,
+		).takeUnless { it.isEmpty }
 	}
 
 	fun setContrast(contrast: Float) {
 		val cf = colorFilter.value
-		colorFilter.value = ReaderColorFilter(cf?.brightness ?: 0f, contrast).takeUnless { it.isEmpty }
+		colorFilter.value = ReaderColorFilter(
+			brightness = cf?.brightness ?: 0f,
+			contrast = contrast,
+			isInverted = cf?.isInverted ?: false,
+		).takeUnless { it.isEmpty }
+	}
+
+	fun setInversion(invert: Boolean) {
+		val cf = colorFilter.value
+		if (invert == cf?.isInverted) {
+			return
+		}
+		colorFilter.value = ReaderColorFilter(
+			brightness = cf?.brightness ?: 0f,
+			contrast = cf?.contrast ?: 0f,
+			isInverted = invert,
+		).takeUnless { it.isEmpty }
 	}
 
 	fun reset() {

app/src/main/kotlin/org/koitharu/kotatsu/reader/ui/colorfilter/DoubleViewTarget.kt

@@ -4,15 +4,15 @@ import android.graphics.drawable.Drawable
 import android.widget.ImageView
 import coil.target.ImageViewTarget
 
-class ShadowViewTarget(
-	view: ImageView,
-	private val shadowView: ImageView,
-) : ImageViewTarget(view) {
+class DoubleViewTarget(
+	primaryView: ImageView,
+	private val secondaryView: ImageView,
+) : ImageViewTarget(primaryView) {
 
 	override var drawable: Drawable?
 		get() = super.drawable
 		set(value) {
 			super.drawable = value
-			shadowView.setImageDrawable(value?.constantState?.newDrawable())
+			secondaryView.setImageDrawable(value?.constantState?.newDrawable())
 		}
 }

app/src/main/kotlin/org/koitharu/kotatsu/reader/ui/config/ReaderSettings.kt

@@ -26,7 +26,7 @@ class ReaderSettings(
 		get() = settings.zoomMode
 
 	val colorFilter: ReaderColorFilter?
-		get() = colorFilterFlow.value
+		get() = colorFilterFlow.value?.takeUnless { it.isEmpty }
 
 	val isPagesNumbersEnabled: Boolean
 		get() = settings.isPagesNumbersEnabled