Line and row scrolling

src/main/kotlin/ru/dbotthepony/mc/otm/client/screen/panels/input/TextInputPanel.kt

@@ -27,6 +27,7 @@ import ru.dbotthepony.mc.otm.client.screen.panels.EditablePanel
 import ru.dbotthepony.mc.otm.core.addAll
 import ru.dbotthepony.mc.otm.core.math.RGBAColor
 import ru.dbotthepony.mc.otm.milliTime
+import kotlin.math.roundToInt
 
 open class TextInputPanel<out S : Screen>(
 	screen: S,
@@ -158,6 +159,18 @@ open class TextInputPanel<out S : Screen>(
 	private val undo = ArrayDeque<Snapshot>()
 	private val redo = ArrayDeque<Snapshot>()
 
+	/**
+	 * scroll in rows (up-down)
+	 */
+	private var scrollLines = 0
+
+	/**
+	 * scroll in pixels (left-right)
+	 */
+	private var scrollPixels = 0f
+
+	var rowSpacing = 2f
+
 	private fun triggerChangeCallback() {
 		if (oldText != lines) {
 			textCache = null
@@ -1018,13 +1031,59 @@ open class TextInputPanel<out S : Screen>(
 		return true
 	}
 
+	private val characterWidthCache = Char2IntOpenHashMap()
+
+	private fun width(char: Char): Int {
+		return characterWidthCache.computeIfAbsent(char, Char2IntFunction { font.width(it.toString()) })
+	}
+
+	private fun width(text: String, beginning: Int = 0, end: Int = text.length - 1): Int {
+		var accumulate = 0
+
+		for (i in beginning.coerceAtLeast(0) .. end.coerceAtMost(text.length - 1)) {
+			accumulate += width(text[i])
+		}
+
+		return accumulate
+	}
+
 	override fun innerRender(stack: PoseStack, mouseX: Float, mouseY: Float, partialTick: Float) {
 		if (!backgroundColor.isFullyTransparent)
 			drawRect(stack, 0f, 0f, width, height, backgroundColor)
 
+		if (multiLine) {
+			val heightInLines = ((height - dockPadding.top - dockPadding.bottom) / (font.lineHeight + rowSpacing)).toInt()
+
+			if (heightInLines > 0) {
+				if (cursorLine < scrollLines) {
+					scrollLines = (cursorLine - 1).coerceAtLeast(0)
+				} else if (heightInLines + scrollLines < cursorLine) {
+					scrollLines = (cursorLine - heightInLines).coerceIn(0, lines.size - 2)
+				}
+			}
+		} else {
+			scrollLines = 0
+		}
+
+		val selectedLine = this[cursorLine]
+
+		if (selectedLine != null) {
+			val w = width(selectedLine, end = cursorRow) - scrollPixels
+
+			if (w < 0f) {
+				scrollPixels = (scrollPixels - 30f).coerceAtLeast(0f)
+			} else if (w >= width - dockPadding.right) {
+				scrollPixels += 30f
+			}
+		}
+
+		stack.pushPose()
+		stack.translate(-scrollPixels, 0f, 0f)
+
 		var y = dockPadding.top
 
-		for ((i, line) in lines.withIndex()) {
+		for (i in scrollLines until lines.size) {
+			val line = lines[i]
 			val selection = selections[i]
 
 			font.drawAligned(
@@ -1046,7 +1105,7 @@ open class TextInputPanel<out S : Screen>(
 					x += font.width(before).toFloat()
 				}
 
-				val width = if (selection.coversNewline(line) && i != lines.size - 1) this.width - x else font.width(selected).toFloat()
+				val width = if (selection.coversNewline(line) && i != lines.size - 1) this.width - x + scrollPixels else font.width(selected).toFloat()
 
 				RenderSystem.setShader(GameRenderer::getPositionShader)
 				RenderSystem.setShaderColor(cursorColor.red, cursorColor.green, cursorColor.blue, 0.4f)
@@ -1060,8 +1119,8 @@ open class TextInputPanel<out S : Screen>(
 
 				builder.begin(VertexFormat.Mode.QUADS, DefaultVertexFormat.POSITION)
 
-				builder.vertex(stack.last().pose(), x, y + font.lineHeight + 2f, 0f).endVertex()
+				builder.vertex(stack.last().pose(), x, y + font.lineHeight + rowSpacing, 0f).endVertex()
-				builder.vertex(stack.last().pose(), x + width, y + font.lineHeight + 2f, 0f).endVertex()
+				builder.vertex(stack.last().pose(), x + width, y + font.lineHeight + rowSpacing, 0f).endVertex()
 				builder.vertex(stack.last().pose(), x + width, y, 0f).endVertex()
 				builder.vertex(stack.last().pose(), x, y, 0f).endVertex()
 
@@ -1073,7 +1132,7 @@ open class TextInputPanel<out S : Screen>(
 				RenderSystem.enableDepthTest()
 			}
 
-			y += font.lineHeight + 2f
+			y += font.lineHeight + rowSpacing
 
 			if (y > height - dockPadding.bottom)
 				break
@@ -1089,7 +1148,7 @@ open class TextInputPanel<out S : Screen>(
 					text = "_",
 					align = TextAlign.TOP_LEFT,
 					x = dockPadding.left + (if (activeLine == null) 0f else font.width(activeLine).toFloat()),
-					y = dockPadding.top + cursorLine * (font.lineHeight + 2f),
+					y = dockPadding.top + (cursorLine - scrollLines) * (font.lineHeight + rowSpacing),
 					color = cursorColor
 				)
 			} else {
@@ -1099,12 +1158,14 @@ open class TextInputPanel<out S : Screen>(
 					text = "|",
 					align = TextAlign.TOP_LEFT,
 					x = dockPadding.left + font.width(activeLine.substring(0, cursorRow)).toFloat() - 1f,
-					y = dockPadding.top + cursorLine * (font.lineHeight + 2f),
+					y = dockPadding.top + (cursorLine - scrollLines) * (font.lineHeight + rowSpacing),
 					color = cursorColor
 				)
 			}
 		}
 
+		stack.popPose()
+
 		if (debugDraw) {
 			font.drawAligned(
 				poseStack = stack,
@@ -1122,7 +1183,7 @@ open class TextInputPanel<out S : Screen>(
 				text = cursorRow.toString(),
 				align = TextAlign.TOP_RIGHT,
 				x = width - dockPadding.right,
-				y = dockPadding.top + font.lineHeight + 2f,
+				y = dockPadding.top + font.lineHeight + rowSpacing,
 				color = cursorColor
 			)
 
@@ -1132,7 +1193,7 @@ open class TextInputPanel<out S : Screen>(
 				text = lines.size.toString(),
 				align = TextAlign.TOP_RIGHT,
 				x = width - dockPadding.right,
-				y = dockPadding.top + font.lineHeight * 2 + 4f,
+				y = dockPadding.top + font.lineHeight * 2f + rowSpacing * 2f,
 				color = cursorColor
 			)
 		}
@@ -1181,19 +1242,20 @@ open class TextInputPanel<out S : Screen>(
 		if (x > width - dockPadding.right)
 			x = width - dockPadding.right
 
-		val line = (y / (font.lineHeight + 2f)).toInt().coerceIn(0, lines.size - 1)
+		x += scrollPixels
+
+		val line = (scrollLines + (y / (font.lineHeight + rowSpacing)).toInt()).coerceIn(0, lines.size - 1)
 		val sLine = this[line] ?: return Vector2i(0, line)
 
 		if (x <= 0f)
 			return Vector2i(0, line)
-		else if (x >= font.width(sLine))
+		else if (x >= width(sLine))
 			return Vector2i(sLine.length, line)
 
-		val cache = Char2IntOpenHashMap()
 		var accumulatedWidth = 0f
 
 		for ((i, char) in sLine.withIndex()) {
-			val width = cache.computeIfAbsent(char, Char2IntFunction { font.width(it.toString()) })
+			val width = width(char)
 
 			if (x in accumulatedWidth .. accumulatedWidth + width) {
 				if (x - accumulatedWidth < width / 2)