<p></p>
<blockquote>
<blockquote>
<p dir="auto">The described behavior doesn't occur when blending two 32 bit Forms.</p>
</blockquote>
<p dir="auto">Would you elaborate on your scenario? How do those lower-depth forms come to be these days?</p>
</blockquote>
<p dir="auto">We use <code class="notranslate">Pen</code>, which is a subclass of <code class="notranslate">BitBlt</code>. More specifically, we use <code class="notranslate">Pen>>roundNib:</code> among others to create a circular brush for painting on a <code class="notranslate">Form</code>. This method creates a <code class="notranslate">Form</code> with depth <code class="notranslate">1</code>. One can then set the color of the brush with <code class="notranslate">Pen>>color:</code>, which calls <code class="notranslate">BitBlt>>fillColor:</code> which in turn sets its <code class="notranslate">halftoneForm</code>. According to the class comment of <code class="notranslate">BitBlt</code>, the pixel values of the <code class="notranslate">halftoneForm</code> are ANDed with the <code class="notranslate">sourceForm</code> pixels before the blending rule is applied.</p>
<p dir="auto">A workaround for us might be to use Pens with 32 bit sourceForms, if that is possible. I only noticed the different behavior of 32 bit forms while trying to create a code snippet to reproduce the problem, so I haven't tried this workaround yet. Also, I think that the problem still occurs when using alpha values between <code class="notranslate">1</code> and <code class="notranslate">254</code>, even if those might not be as noticeable.</p>

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