feat: max frames

evaluator/evaluator.go

@@ -29,10 +29,11 @@ type Evaluator struct {
 	Scale     int
 	Directory string
 	WithGIF   bool
+	MaxFrames int
 }
 
 func New() *Evaluator {
-	return &Evaluator{length: DEFAULT_LENGTH, color: color.RGBA{0, 0, 0, 255}, Scale: 1, Directory: "", WithGIF: false}
+	return &Evaluator{length: DEFAULT_LENGTH, color: color.RGBA{0, 0, 0, 255}, Scale: 1, Directory: "", WithGIF: false, MaxFrames: 0}
 }
 
 func (e *Evaluator) Eval(input io.Reader, path string) image.Image {
@@ -297,6 +298,10 @@ func (e *Evaluator) addGIFFrame() {
 		return
 	}
 
+	if e.MaxFrames > 0 && len(e.GIF.Image) >= e.MaxFrames {
+		return
+	}
+
 	scaled := e.scale()
 	bounds := scaled.Bounds()
 	paletted := image.NewPaletted(bounds, colorPalette(scaled))

evaluator/evaluator_test.go

@@ -682,18 +682,26 @@ func TestNumber(t *testing.T) {
 
 func TestGIF(t *testing.T) {
 	tests := []struct {
-		input    string
-		expected string
+		input     string
+		expected  string
+		MaxFrames int
 	}{
 		{
 			"Repeat C 0 10 { Paper C }",
 			"gradation.gif",
+			0,
+		},
+		{
+			"Repeat C 0 10 { Paper C }",
+			"gradation-half.gif",
+			5,
 		},
 	}
 
 	for i, test := range tests {
 		e := New()
 		e.WithGIF = true
+		e.MaxFrames = test.MaxFrames
 		e.Eval(strings.NewReader(test.input), "test.dbn")
 
 		if len(e.Errors) > 0 {

wasm/index.html

@@ -32,13 +32,15 @@
         <textarea class="form-control border-top-0" rows="10" data-js="text"></textarea>
       </div>
 
-      <div class="mt-3 d-flex align-items-center">
+      <div class="mt-3">
         <button class="btn btn-dark" data-js="run">Run</button>
-        <div class="ms-3 form-check">
-          <input type="checkbox" class="form-check-input" data-js="with-gif" checked>
-          <label class="form-check-label" for="exampleCheck1">GIF</label>
-        </div>
       </div>
+
+      <div class="mt-3 form-check">
+        <input type="checkbox" class="form-check-input" data-js="with-gif" checked>
+        <label class="form-check-label" for="exampleCheck1">GIF</label><br>
+      </div>
+      <p class="text-muted fst-italic small">Limited to 200 frames to avoid hangs on wasm.</p>
     </form>
 
     <div class="mt-3">

wasm/main.go

@@ -62,6 +62,7 @@ func generatePNG(input string) string {
 func generateGIF(input string) string {
 	e := evaluator.New()
 	e.WithGIF = true
+	e.MaxFrames = 200
 
 	e.Eval(strings.NewReader(input), "input")