1 files changed, 69 insertions, 0 deletions
diff --git a/ui/presentation/Sprite.js b/ui/presentation/Sprite.js
new file mode 100644
index 0000000..49ee450
--- /dev/null
+++ b/ui/presentation/Sprite.js
@@ -0,0 +1,69 @@
+import {DisplayElement} from 'tui-lib/ui/primitives'
+
+import * as ansi from 'tui-lib/util/ansi'
+
+export default class Sprite extends DisplayElement {
+  // "A sprite is a two-dimensional bitmap that is integrated into a larger
+  // scene." - Wikipedia
+  //
+  // Sprites are display objects that have a single texture that will not
+  // render outside of their parent.
+  //
+  // Sprites have a "real" position which overrides their "integer" position.
+  // This is so that motion can be more fluid (i.e., sprites don't need to
+  // move a whole number of terminal characters at a time).
+
+  constructor() {
+    super()
+
+    this.texture = []
+
+    this.realX = 0
+    this.realY = 0
+  }
+
+  set x(newX) { this.realX = newX }
+  set y(newY) { this.realY = newY }
+  get x() { return Math.round(this.realX) }
+  get y() { return Math.round(this.realY) }
+
+  drawTo(writable) {
+    if (this.textureAttributes) {
+      writable.write(ansi.setAttributes(this.textureAttributes))
+    }
+
+    for (let y = 0; y < this.textureHeight; y++) {
+      // Don't render above or below the parent's content area.
+      if (this.y + y >= this.parent.contentH || this.y + y < 0) continue
+
+      const right = this.x + this.textureWidth
+
+      const start = (this.x < 0) ? -this.x : 0
+      const end = (
+        (right > this.parent.contentW)
+        ? this.parent.contentW - right
+        : right)
+      const text = this.texture[y].slice(start, end)
+
+      writable.write(ansi.moveCursor(this.absY + y, this.absX + start))
+      writable.write(text)
+    }
+
+    if (this.textureAttributes) {
+      writable.write(ansi.resetAttributes())
+    }
+  }
+
+  fixLayout() {
+    this.w = this.textureWidth
+    this.h = this.textureHeight
+  }
+
+  get textureWidth() {
+    return Math.max(...this.texture.map(row => ansi.measureColumns(row)))
+  }
+
+  get textureHeight() {
+    return this.texture.length
+  }
+}