Added: Terminal CSI reporting of window and cell pixel size

Implement the following CSI escape sequences from
https://invisible-island.net/xterm/ctlseqs/ctlseqs.html:

> CSI Ps ; Ps ; Ps t
> [..]
>    Ps = 1 4  ⇒  Report xterm text area size in pixels.
>    Result is CSI  4 ;  height ;  width t
> [..]
>    Ps = 1 6  ⇒  Report xterm character cell size in pixels.
>    Result is CSI  6 ;  height ;  width t

Extracted from changes in #2973
by @MatanZ and adopted to play well with the just merged #3098 (.ws_xpixel
and .ws_ypixel values in winsize).

terminal-emulator/src/main/java/com/termux/terminal/TerminalEmulator.java

@@ -136,6 +136,9 @@ public final class TerminalEmulator {
     /** The number of character rows and columns in the terminal screen. */
     public int mRows, mColumns;
 
+    /** Size of a terminal cell in pixels. */
+    private int mCellWidthPixels, mCellHeightPixels;
+
     /** The number of terminal transcript rows that can be scrolled back to. */
     public static final int TERMINAL_TRANSCRIPT_ROWS_MIN = 100;
     public static final int TERMINAL_TRANSCRIPT_ROWS_MAX = 50000;
@@ -314,13 +317,15 @@ static int mapDecSetBitToInternalBit(int decsetBit) {
         }
     }
 
-    public TerminalEmulator(TerminalOutput session, int columns, int rows, Integer transcriptRows, TerminalSessionClient client) {
+    public TerminalEmulator(TerminalOutput session, int columns, int rows, int cellWidthPixels, int cellHeightPixels, Integer transcriptRows, TerminalSessionClient client) {
         mSession = session;
         mScreen = mMainBuffer = new TerminalBuffer(columns, getTerminalTranscriptRows(transcriptRows), rows);
         mAltBuffer = new TerminalBuffer(columns, rows, rows);
         mClient = client;
         mRows = rows;
         mColumns = columns;
+        mCellWidthPixels = cellWidthPixels;
+        mCellHeightPixels = cellHeightPixels;
         mTabStop = new boolean[mColumns];
         reset();
     }
@@ -370,7 +375,10 @@ public void sendMouseEvent(int mouseButton, int column, int row, boolean pressed
         }
     }
 
-    public void resize(int columns, int rows) {
+    public void resize(int columns, int rows, int cellWidthPixels, int cellHeightPixels) {
+        this.mCellWidthPixels = cellWidthPixels;
+        this.mCellHeightPixels = cellHeightPixels;
+
         if (mRows == rows && mColumns == columns) {
             return;
         } else if (columns < 2 || rows < 2) {
@@ -1748,8 +1756,10 @@ private void doCsi(int b) {
                         mSession.write("\033[3;0;0t");
                         break;
                     case 14: // Report xterm window in pixels. Result is CSI 4 ; height ; width t
-                        // We just report characters time 12 here.
-                        mSession.write(String.format(Locale.US, "\033[4;%d;%dt", mRows * 12, mColumns * 12));
+                        mSession.write(String.format(Locale.US, "\033[4;%d;%dt", mRows * mCellHeightPixels, mColumns * mCellWidthPixels));
+                        break;
+                    case 16: // Report xterm character cell size in pixels. Result is CSI 6 ; height ; width t
+                        mSession.write(String.format(Locale.US, "\033[6;%d;%dt", mCellHeightPixels, mCellWidthPixels));
                         break;
                     case 18: // Report the size of the text area in characters. Result is CSI 8 ; height ; width t
                         mSession.write(String.format(Locale.US, "\033[8;%d;%dt", mRows, mColumns));

terminal-emulator/src/main/java/com/termux/terminal/TerminalSession.java

@@ -100,12 +100,12 @@ public void updateTerminalSessionClient(TerminalSessionClient client) {
     }
 
     /** Inform the attached pty of the new size and reflow or initialize the emulator. */
-    public void updateSize(int columns, int rows, int fontWidth, int fontHeight) {
+    public void updateSize(int columns, int rows, int cellWidthPixels, int cellHeightPixels) {
         if (mEmulator == null) {
-            initializeEmulator(columns, rows, fontWidth, fontHeight);
+            initializeEmulator(columns, rows, cellWidthPixels, cellHeightPixels);
         } else {
-            JNI.setPtyWindowSize(mTerminalFileDescriptor, rows, columns, fontWidth, fontHeight);
-            mEmulator.resize(columns, rows);
+            JNI.setPtyWindowSize(mTerminalFileDescriptor, rows, columns, cellWidthPixels, cellHeightPixels);
+            mEmulator.resize(columns, rows, cellWidthPixels, cellHeightPixels);
         }
     }
 
@@ -120,11 +120,11 @@ public String getTitle() {
      * @param columns The number of columns in the terminal window.
      * @param rows    The number of rows in the terminal window.
      */
-    public void initializeEmulator(int columns, int rows, int cellWidth, int cellHeight) {
-        mEmulator = new TerminalEmulator(this, columns, rows, mTranscriptRows, mClient);
+    public void initializeEmulator(int columns, int rows, int cellWidthPixels, int cellHeightPixels) {
+        mEmulator = new TerminalEmulator(this, columns, rows, cellWidthPixels, cellHeightPixels, mTranscriptRows, mClient);
 
         int[] processId = new int[1];
-        mTerminalFileDescriptor = JNI.createSubprocess(mShellPath, mCwd, mArgs, mEnv, processId, rows, columns, cellWidth, cellHeight);
+        mTerminalFileDescriptor = JNI.createSubprocess(mShellPath, mCwd, mArgs, mEnv, processId, rows, columns, cellWidthPixels, cellHeightPixels);
         mShellPid = processId[0];
         mClient.setTerminalShellPid(this, mShellPid);
 

terminal-emulator/src/test/java/com/termux/terminal/ControlSequenceIntroducerTest.java

@@ -62,4 +62,24 @@ public void testCsi3J() {
 		assertEquals("y\nz", mTerminal.getScreen().getTranscriptText());
 	}
 
+    public void testReportPixelSize() {
+        int columns = 3;
+        int rows = 3;
+        withTerminalSized(columns, rows);
+        int cellWidth = TerminalTest.INITIAL_CELL_WIDTH_PIXELS;
+        int cellHeight = TerminalTest.INITIAL_CELL_HEIGHT_PIXELS;
+        assertEnteringStringGivesResponse("\033[14t", "\033[4;" + (rows*cellHeight) + ";" + (columns*cellWidth) + "t");
+        assertEnteringStringGivesResponse("\033[16t", "\033[6;" + cellHeight + ";" + cellWidth + "t");
+        columns = 23;
+        rows = 33;
+        resize(columns, rows);
+        assertEnteringStringGivesResponse("\033[14t", "\033[4;" + (rows*cellHeight) + ";" + (columns*cellWidth) + "t");
+        assertEnteringStringGivesResponse("\033[16t", "\033[6;" + cellHeight + ";" + cellWidth + "t");
+        cellWidth = 8;
+        cellHeight = 18;
+        mTerminal.resize(columns, rows, cellWidth, cellHeight);
+        assertEnteringStringGivesResponse("\033[14t", "\033[4;" + (rows*cellHeight) + ";" + (columns*cellWidth) + "t");
+        assertEnteringStringGivesResponse("\033[16t", "\033[6;" + cellHeight + ";" + cellWidth + "t");
+    }
+
 }

terminal-emulator/src/test/java/com/termux/terminal/HistoryTest.java

@@ -11,10 +11,10 @@ public void testHistory() {
 		assertLinesAre("777", "888", "999");
 		assertHistoryStartsWith("666", "555");
 
-		mTerminal.resize(cols, 2);
+		resize(cols, 2);
 		assertHistoryStartsWith("777", "666", "555");
 
-		mTerminal.resize(cols, 3);
+		resize(cols, 3);
 		assertHistoryStartsWith("666", "555");
 	}
 

terminal-emulator/src/test/java/com/termux/terminal/ResizeTest.java

@@ -72,11 +72,11 @@ public void testResizeAfterHistoryWraparound() {
 			enterString("\r\n");
 		}
 		assertLinesAre("998       ", "999       ", "          ");
-		mTerminal.resize(cols, 2);
+		resize(cols, 2);
 		assertLinesAre("999       ", "          ");
-		mTerminal.resize(cols, 5);
+		resize(cols, 5);
 		assertLinesAre("996       ", "997       ", "998       ", "999       ", "          ");
-		mTerminal.resize(cols, rows);
+		resize(cols, rows);
 		assertLinesAre("998       ", "999       ", "          ");
 	}
 

terminal-emulator/src/test/java/com/termux/terminal/TerminalTest.java

@@ -82,7 +82,7 @@ public void testReportTerminalSize() throws Exception {
 		assertEnteringStringGivesResponse("\033[18t", "\033[8;5;5t");
 		for (int width = 3; width < 12; width++) {
 			for (int height = 3; height < 12; height++) {
-				mTerminal.resize(width, height);
+				resize(width, height);
 				assertEnteringStringGivesResponse("\033[18t", "\033[8;" + height + ";" + width + "t");
 			}
 		}

terminal-emulator/src/test/java/com/termux/terminal/TerminalTestCase.java

@@ -13,7 +13,10 @@
 
 public abstract class TerminalTestCase extends TestCase {
 
-	public static class MockTerminalOutput extends TerminalOutput {
+    public static final int INITIAL_CELL_WIDTH_PIXELS = 13;
+    public static final int INITIAL_CELL_HEIGHT_PIXELS = 15;
+
+    public static class MockTerminalOutput extends TerminalOutput {
 		final ByteArrayOutputStream baos = new ByteArrayOutputStream();
 		public final List<ChangedTitle> titleChanges = new ArrayList<>();
 		public final List<String> clipboardPuts = new ArrayList<>();
@@ -108,7 +111,7 @@ protected void setUp() throws Exception {
 
 	protected TerminalTestCase withTerminalSized(int columns, int rows) {
 	    // The tests aren't currently using the client, so a null client will suffice, a dummy client should be implemented if needed
-		mTerminal = new TerminalEmulator(mOutput, columns, rows, rows * 2, null);
+		mTerminal = new TerminalEmulator(mOutput, columns, rows, INITIAL_CELL_WIDTH_PIXELS, INITIAL_CELL_HEIGHT_PIXELS, rows * 2, null);
 		return this;
 	}
 
@@ -201,7 +204,7 @@ public TerminalTestCase assertLinesAre(String... lines) {
 	}
 
 	public TerminalTestCase resize(int cols, int rows) {
-		mTerminal.resize(cols, rows);
+		mTerminal.resize(cols, rows, INITIAL_CELL_WIDTH_PIXELS, INITIAL_CELL_HEIGHT_PIXELS);
 		assertInvariants();
 		return this;
 	}