Fix reflow larger with wide chars

src/Buffer.test.ts

@@ -510,6 +510,43 @@ describe('Buffer', () => {
         assert.equal(secondMarker.line, 1, 'second marker should be restored');
         assert.equal(thirdMarker.line, 2, 'third marker should be restored');
       });
+      it('should wrap wide characters correctly when reflowing larger', () => {
+        buffer.fillViewportRows();
+        buffer.resize(12, 10);
+        for (let i = 0; i < 12; i += 4) {
+          buffer.lines.get(0).set(i, [null, '汉', 2, '汉'.charCodeAt(0)]);
+          buffer.lines.get(1).set(i, [null, '汉', 2, '汉'.charCodeAt(0)]);
+        }
+        for (let i = 2; i < 12; i += 4) {
+          buffer.lines.get(0).set(i, [null, '语', 2, '语'.charCodeAt(0)]);
+          buffer.lines.get(1).set(i, [null, '语', 2, '语'.charCodeAt(0)]);
+        }
+        for (let i = 1; i < 12; i += 2) {
+          buffer.lines.get(0).set(i, [null, '', 0, undefined]);
+          buffer.lines.get(1).set(i, [null, '', 0, undefined]);
+        }
+        buffer.lines.get(1).isWrapped = true;
+        // Buffer:
+        // 汉语汉语汉语 (wrapped)
+        // 汉语汉语汉语
+        assert.equal(buffer.lines.get(0).translateToString(true), '汉语汉语汉语');
+        assert.equal(buffer.lines.get(1).translateToString(true), '汉语汉语汉语');
+        buffer.resize(13, 10);
+        assert.equal(buffer.ybase, 0);
+        assert.equal(buffer.lines.length, 10);
+        assert.equal(buffer.lines.get(0).translateToString(true), '汉语汉语汉语');
+        assert.equal(buffer.lines.get(0).translateToString(false), '汉语汉语汉语 ');
+        assert.equal(buffer.lines.get(1).translateToString(true), '汉语汉语汉语');
+        assert.equal(buffer.lines.get(1).translateToString(false), '汉语汉语汉语 ');
+        buffer.resize(14, 10);
+        assert.equal(buffer.lines.get(0).translateToString(true), '汉语汉语汉语汉');
+        assert.equal(buffer.lines.get(0).translateToString(false), '汉语汉语汉语汉');
+        assert.equal(buffer.lines.get(1).translateToString(true), '语汉语汉语');
+        assert.equal(buffer.lines.get(1).translateToString(false), '语汉语汉语    ');
+      });
+      it('should wrap wide characters correctly when reflowing smaller', () => {
+        // TODO: ..
+      });
 
       describe('reflowLarger cases', () => {
         beforeEach(() => {

src/Buffer.ts

@@ -259,24 +259,36 @@ export class Buffer implements IBuffer {
 
       // Copy buffer data to new locations
       let destLineIndex = 0;
-      let destCol = this._cols;
+      let destCol = wrappedLines[destLineIndex].getTrimmedLength();
       let srcLineIndex = 1;
       let srcCol = 0;
       while (srcLineIndex < wrappedLines.length) {
-        const srcRemainingCells = this._cols - srcCol;
+        const srcTrimmedTineLength = wrappedLines[srcLineIndex].getTrimmedLength();
+        const srcRemainingCells = srcTrimmedTineLength - srcCol;
         const destRemainingCells = newCols - destCol;
         const cellsToCopy = Math.min(srcRemainingCells, destRemainingCells);
+
         wrappedLines[destLineIndex].copyCellsFrom(wrappedLines[srcLineIndex], srcCol, destCol, cellsToCopy, false);
+
         destCol += cellsToCopy;
         if (destCol === newCols) {
           destLineIndex++;
           destCol = 0;
         }
         srcCol += cellsToCopy;
-        if (srcCol === this._cols) {
+        if (srcCol === srcTrimmedTineLength) {
           srcLineIndex++;
           srcCol = 0;
         }
+
+        // Make sure the last cell isn't wide, if it is copy it to the current dest
+        if (destCol === 0) {
+          if (wrappedLines[destLineIndex - 1].getWidth(newCols - 1) === 2) {
+            wrappedLines[destLineIndex].copyCellsFrom(wrappedLines[destLineIndex - 1], newCols - 1, destCol++, 1, false);
+            // Null out the end of the last row
+            wrappedLines[destLineIndex - 1].set(newCols - 1, FILL_CHAR_DATA);
+          }
+        }
       }
 
       // Clear out remaining cells or fragments could remain;

src/BufferLine.ts

@@ -54,6 +54,10 @@ export class BufferLine implements IBufferLine {
     ];
   }
 
+  public getWidth(index: number): number {
+    return this._data[index * CELL_SIZE + Cell.WIDTH];
+  }
+
   public set(index: number, value: CharData): void {
     this._data[index * CELL_SIZE + Cell.FLAGS] = value[0];
     if (value[1].length > 1) {