Expose vips_text to create an image containing rendered text (#3252)

src/common.cc

@@ -133,6 +133,39 @@ namespace sharp {
         descriptor->createBackground = AttrAsVectorOfDouble(input, "createBackground");
       }
     }
+    // Create new image with text
+    if (HasAttr(input, "textValue")) {
+      descriptor->textValue = AttrAsStr(input, "textValue");
+      if (HasAttr(input, "textFont")) {
+        descriptor->textFont = AttrAsStr(input, "textFont");
+      }
+      if (HasAttr(input, "textFontfile")) {
+        descriptor->textFontfile = AttrAsStr(input, "textFontfile");
+      }
+      if (HasAttr(input, "textWidth")) {
+        descriptor->textWidth = AttrAsUint32(input, "textWidth");
+      }
+      if (HasAttr(input, "textHeight")) {
+        descriptor->textHeight = AttrAsUint32(input, "textHeight");
+      }
+      if (HasAttr(input, "textAlign")) {
+        descriptor->textAlign = static_cast<VipsAlign>(
+          vips_enum_from_nick(nullptr, VIPS_TYPE_ALIGN,
+          AttrAsStr(input, "textAlign").data()));
+      }
+      if (HasAttr(input, "textJustify")) {
+        descriptor->textJustify = AttrAsBool(input, "textJustify");
+      }
+      if (HasAttr(input, "textDpi")) {
+        descriptor->textDpi = AttrAsUint32(input, "textDpi");
+      }
+      if (HasAttr(input, "textRgba")) {
+        descriptor->textRgba = AttrAsBool(input, "textRgba");
+      }
+      if (HasAttr(input, "textSpacing")) {
+        descriptor->textSpacing = AttrAsUint32(input, "textSpacing");
+      }
+    }
     // Limit input images to a given number of pixels, where pixels = width * height
     descriptor->limitInputPixels = static_cast<uint64_t>(AttrAsInt64(input, "limitInputPixels"));
     // Allow switch from random to sequential access
@@ -395,6 +428,34 @@ namespace sharp {
         }
         image = image.cast(VIPS_FORMAT_UCHAR);
         imageType = ImageType::RAW;
+      } else if (descriptor->textValue.length() > 0) {
+        // Create a new image with text
+        vips::VOption *textOptions = VImage::option()
+          ->set("align", descriptor->textAlign)
+          ->set("justify", descriptor->textJustify)
+          ->set("rgba", descriptor->textRgba)
+          ->set("spacing", descriptor->textSpacing)
+          ->set("autofit_dpi", &descriptor->textAutofitDpi);
+        if (descriptor->textWidth > 0) {
+          textOptions->set("width", descriptor->textWidth);
+        }
+        // Ignore dpi if height is set
+        if (descriptor->textWidth > 0 && descriptor->textHeight > 0) {
+          textOptions->set("height", descriptor->textHeight);
+        } else if (descriptor->textDpi > 0) {
+          textOptions->set("dpi", descriptor->textDpi);
+        }
+        if (descriptor->textFont.length() > 0) {
+          textOptions->set("font", const_cast<char*>(descriptor->textFont.data()));
+        }
+        if (descriptor->textFontfile.length() > 0) {
+          textOptions->set("fontfile", const_cast<char*>(descriptor->textFontfile.data()));
+        }
+        image = VImage::text(const_cast<char *>(descriptor->textValue.data()), textOptions);
+        if (!descriptor->textRgba) {
+          image = image.copy(VImage::option()->set("interpretation", VIPS_INTERPRETATION_B_W));
+        }
+        imageType = ImageType::RAW;
       } else {
         // From filesystem
         imageType = DetermineImageType(descriptor->file.data());

src/common.h

@@ -71,6 +71,17 @@ namespace sharp {
     std::string createNoiseType;
     double createNoiseMean;
     double createNoiseSigma;
+    std::string textValue;
+    std::string textFont;
+    std::string textFontfile;
+    int textWidth;
+    int textHeight;
+    VipsAlign textAlign;
+    bool textJustify;
+    int textDpi;
+    bool textRgba;
+    int textSpacing;
+    int textAutofitDpi;
 
     InputDescriptor():
       buffer(nullptr),
@@ -95,7 +106,15 @@ namespace sharp {
       createHeight(0),
       createBackground{ 0.0, 0.0, 0.0, 255.0 },
       createNoiseMean(0.0),
-      createNoiseSigma(0.0) {}
+      createNoiseSigma(0.0),
+      textWidth(0),
+      textHeight(0),
+      textAlign(VIPS_ALIGN_LOW),
+      textJustify(FALSE),
+      textDpi(72),
+      textRgba(FALSE),
+      textSpacing(0),
+      textAutofitDpi(0) {}
   };
 
   // Convenience methods to access the attributes of a Napi::Object

src/pipeline.cc

@@ -1185,6 +1185,10 @@ class PipelineWorker : public Napi::AsyncWorker {
         info.Set("trimOffsetTop", static_cast<int32_t>(baton->trimOffsetTop));
       }
 
+      if (baton->input->textAutofitDpi) {
+        info.Set("textAutofitDpi", static_cast<uint32_t>(baton->input->textAutofitDpi));
+      }
+
       if (baton->bufferOutLength > 0) {
         // Add buffer size to info
         info.Set("size", static_cast<uint32_t>(baton->bufferOutLength));