app: harden mirroring lifecycle and state

1 files changed, 46 insertions, 0 deletions

diff --git a/app/src/main/java/invalid/lena/scrcpy/TouchGeometry.java b/app/src/main/java/invalid/lena/scrcpy/TouchGeometry.java
new file mode 100644
index 0000000..5ee80d4
--- /dev/null
+++ b/app/src/main/java/invalid/lena/scrcpy/TouchGeometry.java
@@ -0,0 +1,46 @@
+package invalid.lena.scrcpy;
+
+// Publishes a target size and its matching on-screen viewport as one
+// immutable value. A target resize invalidates the old viewport until the UI
+// lays out the new generation.
+final class TouchGeometry {
+
+    static final class Snapshot {
+        final int targetW, targetH;
+        final int x, y, w, h;
+
+        Snapshot(int targetW, int targetH, int x, int y, int w, int h) {
+            this.targetW = targetW;
+            this.targetH = targetH;
+            this.x = x;
+            this.y = y;
+            this.w = w;
+            this.h = h;
+        }
+    }
+
+    private volatile Snapshot snapshot;
+    private long version;
+    private int targetW;
+    private int targetH;
+
+    synchronized void setTargetSize(long nextVersion, int w, int h) {
+        if (nextVersion <= version) throw new IllegalArgumentException("stale target version");
+        if (w <= 0 || h <= 0) throw new IllegalArgumentException("invalid target size");
+        version = nextVersion;
+        targetW = w;
+        targetH = h;
+        snapshot = null;
+    }
+
+    synchronized void setViewport(long expectedVersion, int x, int y, int w, int h) {
+        if (expectedVersion != version) return;
+        snapshot = version > 0 && targetW > 0 && targetH > 0 && w > 0 && h > 0
+                ? new Snapshot(targetW, targetH, x, y, w, h)
+                : null;
+    }
+
+    Snapshot snapshot() {
+        return snapshot;
+    }
+}