Android Guides Drawing comparison

Drawing Overlay Comparison

CPDFCompareDrawings overlays two documents to produce a new PDF for inspecting drawing revisions. Colors and opacity apply to the overlay result. For structured difference lists, use Content Comparison.

Generate and Save the Result

baseDocument and comparedDocument are open. outputPath is a separate output path whose parent directory exists. Run comparison and saving on a background thread.

import android.graphics.Color;
import com.compdfkit.core.compare.CPDFCompareDrawings;
import com.compdfkit.core.document.CPDFDocument;
import com.compdfkit.core.common.CPDFDocumentException;

CPDFCompareDrawings drawings = baseDocument.createCompareDrawings(comparedDocument);
if (drawings != null) {
    CPDFDocument generated = null;
    try {
        drawings.setColorCompare(Color.RED);
        drawings.setColorCompared(Color.BLUE);
        drawings.setFillAlphaCompare(0.5f);
        drawings.setFillAlphaCompared(0.5f);
        drawings.setStrokeAlphaCompare(1.0f);
        drawings.setStrokeAlphaCompared(1.0f);
        drawings.setBlendMode(CPDFCompareDrawings.BlendMode.MULTIPLY);
        if (drawings.compareContent()) {
            generated = drawings.getDocGenerate(context);
            if (generated != null) {
                boolean saved = generated.saveAs(outputPath, false);
                // Handle the save result.
            }
        }
    } catch (CPDFDocumentException e) {
        // Handle output path or save errors.
    } finally {
        if (generated != null) {
            generated.close();
        }
        drawings.close();
    }
}

Configuration and Lifecycle

Method	Description
setColorCompare(), setColorCompared()	Set colors for the base and compared documents
setFillAlphaCompare(), setFillAlphaCompared()	Set fill opacity from 0 to 1
setStrokeAlphaCompare(), setStrokeAlphaCompared()	Set stroke opacity from 0 to 1
setBlendMode()	Set the BlendMode
compareContent()	Generates the overlay and returns whether it succeeded
getDocGenerate(context)	Gets the generated document; may return null if generation did not succeed

The caller owns the generated document and must close it before closing the comparison object. Repeated calls to getDocGenerate() return the same instance.

After retrieving the document, do not call compareContent() again on that comparison object. Create a new object for another comparison. The generated document has no original file path, so save it with saveAs(), not save().