fix: 压缩RDP实时画面传输

- 将原始RGBA位图压缩为PNG后通过WebSocket发送
- 降低低带宽代理链路下的RDP首帧延迟
- 增加位图压缩与异常数据测试

backend/controller/rdp.go

@@ -658,7 +658,7 @@ func isMostlyBlackRGBA(img *image.RGBA, threshold float64) bool {
 func writeRDPFrame(mgr *wshub.WSManager, conn *websocket.Conn, frame rdpengine.ServerFrame) error {
 	mgr.SetWriteDeadline(conn)
 	if frame.Type == "bitmap" && len(frame.RGBA) > 0 {
-		return conn.WriteMessage(websocket.BinaryMessage, encodeRDPBitmapBinary(frame))
+		return writeCompressedRDPBitmap(conn, frame)
 	}
 	return conn.WriteJSON(frame)
 }

backend/controller/rdp_live_frame.go

@@ -0,0 +1,48 @@
+package controller
+
+import (
+	"bytes"
+	"encoding/base64"
+	"fmt"
+	"image"
+	"image/png"
+
+	rdpengine "ezops/pkg/rdp"
+
+	"github.com/gorilla/websocket"
+)
+
+// encodeRDPBitmapPNG 将实时 RGBA 脏矩形压缩为 PNG，避免原始整帧占满低带宽 WebSocket。 // Logan.Li
+func encodeRDPBitmapPNG(frame rdpengine.ServerFrame) (rdpengine.ServerFrame, error) {
+	if frame.Type != "bitmap" || len(frame.RGBA) == 0 {
+		return frame, nil
+	}
+	if frame.Width <= 0 || frame.Height <= 0 {
+		return rdpengine.ServerFrame{}, fmt.Errorf("RDP 位图尺寸无效: %dx%d", frame.Width, frame.Height)
+	}
+	required := frame.Width * frame.Height * 4
+	if len(frame.RGBA) < required {
+		return rdpengine.ServerFrame{}, fmt.Errorf("RDP 位图数据不足: got=%d want=%d", len(frame.RGBA), required)
+	}
+
+	img := image.NewRGBA(image.Rect(0, 0, frame.Width, frame.Height))
+	copy(img.Pix, frame.RGBA[:required])
+	var buf bytes.Buffer
+	encoder := png.Encoder{CompressionLevel: png.BestSpeed}
+	if err := encoder.Encode(&buf, img); err != nil {
+		return rdpengine.ServerFrame{}, fmt.Errorf("压缩 RDP 位图失败: %w", err)
+	}
+
+	frame.Image = "data:image/png;base64," + base64.StdEncoding.EncodeToString(buf.Bytes())
+	frame.RGBA = nil
+	return frame, nil
+}
+
+// writeCompressedRDPBitmap 发送浏览器已支持的 JSON PNG 帧，兼容现有前端绘制逻辑。 // Logan.Li
+func writeCompressedRDPBitmap(conn *websocket.Conn, frame rdpengine.ServerFrame) error {
+	encoded, err := encodeRDPBitmapPNG(frame)
+	if err != nil {
+		return err
+	}
+	return conn.WriteJSON(encoded)
+}

backend/controller/rdp_live_frame_test.go

@@ -0,0 +1,66 @@
+package controller
+
+import (
+	"bytes"
+	"encoding/base64"
+	"image/png"
+	"strings"
+	"testing"
+
+	rdpengine "ezops/pkg/rdp"
+)
+
+func TestEncodeRDPBitmapPNGCompressesFrame(t *testing.T) {
+	const width = 900
+	const height = 540
+	rgba := make([]byte, width*height*4)
+	for i := 0; i < len(rgba); i += 4 {
+		rgba[i+3] = 255
+	}
+
+	encoded, err := encodeRDPBitmapPNG(rdpengine.ServerFrame{
+		Type:   "bitmap",
+		X:      12,
+		Y:      34,
+		Width:  width,
+		Height: height,
+		RGBA:   rgba,
+	})
+	if err != nil {
+		t.Fatalf("压缩 RDP 位图失败: %v", err)
+	}
+	if len(encoded.RGBA) != 0 {
+		t.Fatalf("压缩后仍携带原始 RGBA: %d", len(encoded.RGBA))
+	}
+	const prefix = "data:image/png;base64,"
+	if !strings.HasPrefix(encoded.Image, prefix) {
+		t.Fatalf("压缩帧格式错误: %q", encoded.Image[:min(len(encoded.Image), len(prefix))])
+	}
+	pngData, err := base64.StdEncoding.DecodeString(strings.TrimPrefix(encoded.Image, prefix))
+	if err != nil {
+		t.Fatalf("解码 PNG 数据失败: %v", err)
+	}
+	img, err := png.Decode(bytes.NewReader(pngData))
+	if err != nil {
+		t.Fatalf("解析 PNG 数据失败: %v", err)
+	}
+	if img.Bounds().Dx() != width || img.Bounds().Dy() != height {
+		t.Fatalf("PNG 尺寸错误: got=%dx%d", img.Bounds().Dx(), img.Bounds().Dy())
+	}
+	if len(encoded.Image) >= len(rgba)/4 {
+		t.Fatalf("PNG 压缩率不足: encoded=%d raw=%d", len(encoded.Image), len(rgba))
+	}
+	t.Logf("RDP 帧压缩: raw=%d encoded=%d", len(rgba), len(encoded.Image))
+}
+
+func TestEncodeRDPBitmapPNGRejectsShortPayload(t *testing.T) {
+	_, err := encodeRDPBitmapPNG(rdpengine.ServerFrame{
+		Type:   "bitmap",
+		Width:  10,
+		Height: 10,
+		RGBA:   make([]byte, 8),
+	})
+	if err == nil {
+		t.Fatal("短位图数据应返回错误")
+	}
+}