{"id":108051,"date":"2023-04-14T07:00:00","date_gmt":"2023-04-14T14:00:00","guid":{"rendered":"https:\/\/devblogs.microsoft.com\/oldnewthing\/?p=108051"},"modified":"2023-04-13T17:43:23","modified_gmt":"2023-04-14T00:43:23","slug":"20230414-00","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/oldnewthing\/20230414-00\/?p=108051","title":{"rendered":"How can I convert a WIC bitmap to a Windows Runtime SoftwareBitmap? part 4: Handing it over"},"content":{"rendered":"

Last time, we converted a WIC bitmap to a Windows Runtime SoftwareBitmap by copying the pixels of the WIC bitmap directly into the SoftwareBitmap<\/a>. But you don’t even have to copy pixels at all!<\/p>\n

The ISoftware\u00adBitmap\u00adNative\u00adFactory::Create\u00adFrom\u00adWIC\u00adBitmap<\/code> method<\/a> gives you a direct transfer of a IWICBitmap<\/code> into a SoftwareBitmap<\/code>.<\/p>\n

#include <windows.graphics.imaging.interop.h>\r\n\r\nwinrt::SoftwareBitmap ToSoftwareBitmap(IWICBitmap* wicBitmap)\r\n{\r\n    winrt::SoftwareBitmap bitmap{ nullptr };\r\n\r\n    auto native = winrt::create_instance<\r\n        ISoftwareBitmapNativeFactory>(\r\n        CLSID_SoftwareBitmapNativeFactory);\r\n\r\n    winrt::check_hresult(native->CreateFromWICBitmap(\r\n        wicBitmap, true, winrt::guid_of<winrt::SoftwareBitmap>(),\r\n        winrt::put_abi(bitmap)));\r\n\r\n    return bitmap;\r\n}\r\n<\/pre>\n
First, we create a null Software\u00adBitmap<\/code> that will hold the result.<\/p>\n
Next, we ask for the ISoftware\u00adBitmap\u00adNative\u00adFactory<\/code> interface from a Software\u00adBitmap\u00adNative\u00adFactory<\/code>.<\/p>\n
Finally, we call the Create\u00adFrom\u00adWIC\u00adBitmap<\/code> method to transmogrify the wicBitmap<\/code> into a Software\u00adBitmap<\/code>, saying that the resulting bitmap is read-only (true<\/code>).<\/p>\n
And then we return the resulting bitmap.<\/p>\n
The Software\u00adBitmap<\/code> doesn’t make a copy of the IWICBitmap<\/code>. It just copies the reference. As a result, no pixels are copied at all!<\/p>\n
Since the Software\u00adBitmap<\/code> has a reference to the original IWICBitmap<\/code>, you have two usage patterns.<\/p>\n
If you are “giving away” the IWICBitmap<\/code>, then you can pass forceReadOnly = false<\/code> to make the resulting Software\u00adBitmap<\/code> read-write. The Software\u00adBitmap<\/code> now owns the IWICBitmap<\/code> and may choose to modify it.<\/p>\n
If you are sharing the IWICBitmap<\/code>, then pass forceReadOnly = true<\/code> to make the resulting Software\u00adBitmap<\/code> read-only. That way, the Software\u00adBitmap<\/code> won’t make changes to the IWICBitmap<\/code>.<\/p>\n
If your IWICBitmap<\/code> is a no-cache bitmap created from a IWICBitmapSource<\/code>, then you need to pass forceReadOnly = true<\/code> because the pixels are being generated on the fly and there is no buffer to modify.<\/p>\n
I wrote out the above sequence in multiple steps, but you can collapse it into a one-liner:<\/p>\n
winrt::SoftwareBitmap ToSoftwareBitmap(IWICBitmap* wicBitmap)\r\n{\r\n    return winrt::capture(\r\n        winrt::create_instance\r\n            <ISoftwareBitmapNativeFactory>\r\n            (CLSID_SoftwareBitmapNativeFactory),\r\n        &ISoftwareBitmapNativeFactory::CreateFromWICBitmap,\r\n        wicBitmap, false);\r\n}\r\n<\/pre>\n
Note that this call will fail if the IWICBitmap<\/code> is in a format not supported by Software\u00adBitmap<\/code>.<\/p>\n
Bonus chatter<\/b>: A Software\u00adBitmap<\/code> can have an IWICBitmap<\/code> inside it, or it can have a IMF2DBuffer<\/code> inside (for video formats like NV12). If you have a Software\u00adBitmap<\/code>, you can reach inside and access the inner bitmap buffer by using ISoftware\u00adBitmap\u00adNative::Get\u00adData<\/code>.<\/p>\n","protected":false},"excerpt":{"rendered":"
Just take the whole thing.<\/p>\n","protected":false},"author":1069,"featured_media":111744,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[25],"class_list":["post-108051","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-oldnewthing","tag-code"],"acf":[],"blog_post_summary":"
Just take the whole thing.<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/108051","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/users\/1069"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/comments?post=108051"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/108051\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media\/111744"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media?parent=108051"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/categories?post=108051"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/tags?post=108051"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}