I've seen here that you can create an image list with transparency. It works... sort of.
I used this to create an image list for a list control. The results were a little disappointing:
The one on the left is how it should look. The one on the right is how the list control is displaying it. It looks like it just tried to use the alpha as a mask and any blended area is attempted to be approximated by dithering. Is there a way of getting this better so that I get an actual alpha blended image?
Here is the source if that makes any difference:
class CDlg : public CDialog
{
DECLARE_DYNCREATE(CDlg)
public:
CDlg(CWnd* pParent = NULL); // standard constructor
virtual ~CDlg();
// Dialog Data
enum { IDD = IDD_BS_PRINT };
CGdiPlusBitmapResource m_pBitmap;
protected:
virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support
virtual BOOL OnInitDialog();
DECLARE_MESSAGE_MAP()
public:
CListCtrl m_printOptions;
};
BOOL CDlg::OnInitDialog()
{
__super::OnInitDialog();
m_pBitmap.Load(IDB_RIBBON_HOMELARGE, _T("PNG"), AfxGetResourceHandle());
HBITMAP hBitmap;
m_pBitmap.m_pBitmap->GetHBITMAP(RGB(0, 0, 0), &hBitmap);
CImageList *pList = new CImageList;
CBitmap bm;
bm.Attach(hBitmap);
pList->Create(32, 32, ILC_COLOR32, 0, 4);
pList->Add(&bm, RGB(255, 0, 255));
m_printOptions.SetImageList(pList, LVSIL_NORMAL);
//...
return TRUE;
}
IMPLEMENT_DYNCREATE(CDlg, CDialog)
CBSPrintDlg::CBSPrintDlg(CWnd* pParent /*=NULL*/)
: CBCGPDialog(CBSPrintDlg::IDD, pParent)
{
}
CBSPrintDlg::~CBSPrintDlg()
{
}
void CBSPrintDlg::DoDataExchange(CDataExchange* pDX)
{
CBCGPDialog::DoDataExchange(pDX);
DDX_Control(pDX, IDC_PRINT_OPTIONS, m_printOptions);
}
For source of CGdiPlusBitmapResource implementation look here.
The original image with transparency is this:
#Barmak tried with a different image and it looks fine. I think that is because the transparency is near the edge and not located within the image. See here:
Edit ----------
First parameter in Gdiplus::GetHBITMAP should be the background color. Using RGB(0, 0, 0) as background color causes the semi-transparent pixels to match with black.
Using Gdiplus::Color(255,255,255,255) (white) it will improve the appearance (because ListView background is also white). But it's better to change the background to Gdiplus::Color(0,255,255,255) (transparent) to match any background.
{
CGdiPlusBitmapResource gdibmp;
if (gdibmp.Load(IDB_RIBBON_HOMELARGE, _T("PNG"), AfxGetResourceHandle()))
{
HBITMAP hBitmap;
gdibmp.m_pBitmap->GetHBITMAP(Gdiplus::Color::Transparent, &hBitmap);
ImageList_AddMasked(*pList, hBitmap, 0);
}
}
This assume images are all 32x32 pixels. If images are different sizes, they have to be resized before being added to image list.
{
CGdiPlusBitmapResource gdibmp;
if (gdibmp.Load(id, _T("PNG"), AfxGetResourceHandle()))
{
//resize image to 32x32 pixels
Gdiplus::Bitmap newBmp(32, 32, PixelFormat32bppPARGB);
double oldh = (double)gdibmp.m_pBitmap->GetHeight();
double oldw = (double)gdibmp.m_pBitmap->GetWidth();
double neww = 32;
double newh = 32;
double ratio = oldw / oldh;
if (oldw > oldh)
newh = neww / ratio;
else
neww = newh * ratio;
Gdiplus::Graphics graphics(&newBmp);
graphics.SetInterpolationMode(Gdiplus::InterpolationMode::InterpolationModeHighQualityBicubic);
graphics.SetSmoothingMode(Gdiplus::SmoothingModeAntiAlias);
graphics.DrawImage(gdibmp.m_pBitmap, 0, 0, (int)neww, (int)newh);
//add `newBmp` to image list
HBITMAP hBitmap;
newBmp.GetHBITMAP(Gdiplus::Color::Transparent, &hBitmap);
ImageList_AddMasked(m_ImageList, hBitmap, 0);
}
}
Using GdiPlus::GetHICON to get the icon handle... With CGdiPlusBitmapResource class, it should be possible to use the following:
HICON hicon;
m_pBitmap.Load(IDB_RIBBON_HOMELARGE, _T("PNG"), AfxGetResourceHandle());
m_pBitmap.m_pBitmap->GetHICON(&hicon);
pList->Add(hicon);
or using GetHBITMAP
Also make sure Visual Styles is enabled for improved appearance of ListView icons.
Test image with transparent background:
The PNG image contains pixels that are partially transparent (alpha < 255). That's a pretty common accident with a program like Photoshop, the most likely cause is overlaying the spyglass image on top of the document image and not merging the layers correctly.
As given, the image can only look good when it is displayed on top of the light-gray or white background. But that didn't happen, the background was black. Now making the anti-aliasing pixels around the spyglass painfully obvious, they turned various shades of dark-gray depending on their alpha value and no longer blend with the white background of the document image. A very typical mishap when you use GDI functions, it does not like alpha.
You can doctor it with GDI+, ensuring that the background color is correct. But that's a fair amount of work and it still leaves you with the trouble of guessing at the original background color correctly.
Just really rather best to go back to whatever painting tool you used and fix the problem there. Quickest fix ought to be re-saving it as a 24bpp BMP image file, ymmv.
Related
I created an app in which I want to display text on top of google maps. I chose to use custom markers, but they can only be images, so I decided to create an image from my text utilizing SkiaSharp.
private static ImageSource CreateImageSource(string text)
{
int numberSize = 20;
int margin = 5;
SKBitmap bitmap = new SKBitmap(30, numberSize + margin * 2, SKImageInfo.PlatformColorType, SKAlphaType.Premul);
SKCanvas canvas = new SKCanvas(bitmap);
SKPaint paint = new SKPaint
{
Style = SKPaintStyle.StrokeAndFill,
TextSize = numberSize,
Color = SKColors.Red,
StrokeWidth = 1,
};
canvas.DrawText(text.ToString(), 0, numberSize, paint);
SKImage skImage = SKImage.FromBitmap(bitmap);
SKData data = skImage.Encode(SKEncodedImageFormat.Png, 100);
return ImageSource.FromStream(data.AsStream);
}
The images I create however have ugly artifacts on the top of the resulting image and my feeling is that they get worse if I create multiple images.
I built an example app, that shows the artifacts and the code I used to draw the text. It can be found here:
https://github.com/hot33331/SkiaSharpExample
How can I get rid of those artifacts. Am I using skia wrong?
I got the following answer from Matthew Leibowitz on the SkiaSharp GitHub:
The chances are you are not clearing the canvas/bitmap first.
You can either do bitmap.Erase(SKColors.Transparent) or canvas.Clear(SKColors.Transparent) (you can use any color).
The reason for this is performance. When creating a new bitmap, the computer has no way of knowing what background color you want. So, if it was to go transparent and you wanted white, then there would be two draw operations to clear the pixels (and this may be very expensive for large images).
During the allocation of the bitmap, the memory is provided, but the actual data is untouched. If there was anything there previously (which there will be), this data appears as colored pixels.
When I've seen that before, it's been because the memory passed to SkiaSharp was not zeroed. As an optimization, though, Skia assumes that the memory block passed to it is pre zeroed. Resultingly, if your first operation is a clear, it will ignore that operation, because it thinks that the state is already clean. To resolve this issue, you can manually zero the memory passed to SkiaSharp.
public static SKSurface CreateSurface(int width, int height)
{
// create a block of unmanaged native memory for use as the Skia bitmap buffer.
// unfortunately, this may not be zeroed in some circumstances.
IntPtr buff = System.Runtime.InteropServices.Marshal.AllocCoTaskMem(width * height * 4);
byte[] empty = new byte[width * height * 4];
// copy in zeroed memory.
// maybe there's a more sanctioned way to do this.
System.Runtime.InteropServices.Marshal.Copy(empty, 0, buff, width * height * 4);
// create the actual SkiaSharp surface.
var colorSpace = CGColorSpace.CreateDeviceRGB();
var bContext = new CGBitmapContext(buff, width, height, 8, width * 4, colorSpace, (CGImageAlphaInfo)bitmapInfo);
var surface = SKSurface.Create(width, height, SKColorType.Rgba8888, SKAlphaType.Premul, bitmap.Data, width * 4);
return surface;
}
Edit: btw, I assume this is a bug in SkiaSharp. The samples/apis that create the buffer for you should probably be zeroing it out. Depending on the platform it can be hard to repro as the memory alloc behaves differently. More or less likely to provide you untouched memory.
My question is related to this previous question. What I want to achieve is to stack images (they have transparency), write a string on top, and save the photomontage / photocollage with full resolution.
#Override
protected void beforeMain(Form f) {
Image photoBase = fetchResourceFile().getImage("Voiture_4_3.jpg");
Image watermark = fetchResourceFile().getImage("Watermark.png");
f.setLayout(new LayeredLayout());
final Label drawing = new Label();
f.addComponent(drawing);
// Image mutable dans laquelle on va dessiner (fond blanc)
Image mutableImage = Image.createImage(photoBase.getWidth(), photoBase.getHeight());
drawing.getUnselectedStyle().setBgImage(mutableImage);
drawing.getUnselectedStyle().setBackgroundType(Style.BACKGROUND_IMAGE_SCALED_FIT);
// Paint all the stuff
paints(mutableImage.getGraphics(), photoBase, watermark, photoBase.getWidth(), photoBase.getHeight());
// Save the collage
Image screenshot = Image.createImage(photoBase.getWidth(), photoBase.getHeight());
f.revalidate();
f.setVisible(true);
drawing.paintComponent(screenshot.getGraphics(), true);
String imageFile = FileSystemStorage.getInstance().getAppHomePath() + "screenshot.png";
try(OutputStream os = FileSystemStorage.getInstance().openOutputStream(imageFile)) {
ImageIO.getImageIO().save(screenshot, os, ImageIO.FORMAT_PNG, 1);
} catch(IOException err) {
err.printStackTrace();
}
}
public void paints(Graphics g, Image background, Image watermark, int width, int height) {
g.drawImage(background, 0, 0);
g.drawImage(watermark, 0, 0);
g.setColor(0xFF0000);
// Upper left corner
g.fillRect(0, 0, 10, 10);
// Lower right corner
g.setColor(0x00FF00);
g.fillRect(width - 10, height - 10, 10, 10);
g.setColor(0xFF0000);
Font f = Font.createTrueTypeFont("Geometos", "Geometos.ttf").derive(220, Font.STYLE_BOLD);
g.setFont(f);
// Draw a string right below the M from Mercedes on the car windscreen (measured in Gimp)
g.drawString("HelloWorld",
(int) (848 ),
(int) (610)
);
}
This is the saved screenshot I get if I use the Iphone6 skin (the payload image is smaller than the original one and is centered). If I use the Xoom skin this is what I get (the payload image is still smaller than the original image but it has moved to the left).
So to sum it all up : why is the saved screenshot with Xoom skin different from the one I get with Iphone skin ? Is there anyway to directly save the graphics on which I paint in the paints method so that the saved image would have the original dimensions ?
Thanks a lot to anyone that could help me :-)!
Cheers,
You can save an image in Codename one using the ImageIO class. Notice that you can draw a container hierarchy into a mutable image using the paintComponent(Graphics) method.
You can do both approaches with draw image on mutable or via layouts. Personally I always prefer layouts as I like the abstraction but I wouldn't say the mutable image approach is right/wrong.
Notice that if you change/repaint a lot then mutable images are slower (this will not be noticeable for regular code or on the simulator) as they are forced to use the software renderer and can't use the GPU fully.
In the previous question it seems you placed the image with a "FIT" style which naturally drew it smaller than the containing container and then drew the image on top of it manually... This is problematic.
One solution is to draw everything manually but then you will need to do the "fit" aspect of drawing yourself. If you use layouts you should position everything based on the layouts including your drawing/text.
I'm developing a UI system that has all those smart features like panel tearing off and docking, etc. Right now my task is to create an overlay on the screen that shows the position where the teared off or dockable panel would land. Pretty much same thing that visual studio has got.
For that I'm using a custom layered window class that would show up when it is needed. After that I've started digging to achieve the needed effect.
I was working with standart GDI functions before and basicly they are ok. But this time I followed the documentation advice to use UpdateLayeredWindow for my tasks and to load 32bit image from bitmap instead of drawing it with GDI functions.
So here I have a 128x128pixel wide bmp with 222 in alpha channel and 255 0 0 in RGB
Here are methods which I use for initialization and drawing.
void Init(HDC in_hdc,HWND in_hwnd)
{
bf = { 0, 0, 200, AC_SRC_ALPHA };
hwnd = in_hwnd;
hdc_mem = CreateCompatibleDC(in_hdc);
hBitmap_mem = CreateCompatibleBitmap(in_hdc, canvas_size.cx, canvas_size.cy);
hBitmap_mem_default = (HBITMAP)SelectObject(hdc_mem, hBitmap_mem);
hdc_bitmap = CreateCompatibleDC(in_hdc);
}
void DrawArea(RECT& in_rect)
{
hBitmap_area_default = (HBITMAP)SelectObject(hdc_bitmap, hBitmap_area);
AlphaBlend(hdc_mem, in_rect.left, in_rect.top, in_rect.right, in_rect.bottom, hdc_bitmap, 0, 0, 2, 2, bf);
hBitmap_area = (HBITMAP)SelectObject(hdc_bitmap, hBitmap_area_default);
}
void Update()
{
POINT p = { 0, 0 };
HDC hdc_screen = GetDC(0);
UpdateLayeredWindow(hwnd, hdc_screen, &p, &canvas_size, hdc_mem, &p, 0, &bf, ULW_ALPHA);
}
The window style has this extras
WS_EX_LAYERED|WS_EX_TRANSPARENT|WS_EX_TOPMOST
And here is what I get.
So as you can see the blending that takes place DOES take into account per-pixel alpha, but it does a bad blending job.
Any ideas how to tune it?
I suspect the problem is in the source bitmap. This is the kind of effect you get when the RGB values aren't premultiplied with the alpha. But ignore that because there is a far simpler way of doing this.
Create a layered window with a solid background colour by setting hbrBackground in the WNDCLASSEX structure.
Make the window partially transparent by calling SetLayeredWindowAttributes.
Position the window where you want it.
That's it.
This answer has code that illustrates the technique for a slightly different purpose.
I am taking Pebble example of working with APNG and trying to mask it with transparent text, so bitmap will show only thru text, but no matter what mask/composite mode I try, bitmap is shown as black-and-white (original animation is in color and shows in color if I don't draw text)
Here's a sample code I use in callback SP for the layer that draws text:
//creating background and text
graphics_context_set_fill_color(ctx, GColorBlack);
graphics_fill_rect(ctx, GRect(0, 0, 144, 168), 0, GCornerNone);
graphics_context_set_text_color(ctx, GColorWhite);
graphics_draw_text(ctx, "08:39", fonts_get_system_font(FONT_KEY_ROBOTO_BOLD_SUBSET_49), GRect(0,50,144,118), GTextOverflowModeFill, GTextAlignmentCenter, NULL);
//drawing bitmap (extracted from bitmap_sequence elsewhere)
graphics_context_set_compositing_mode(ctx, GCompOpClear);
graphics_draw_bitmap_in_rect(ctx, s_bitmap, GRect(0,0,144,168));
Any idea how to have actual color bitmap to show thru?
Ok, I finally managed it but not sure if this is the best way. I basically capture framebuffer of current layer and then loop thru every pixel, copying there source bitmap byte by byte, but only when white pixels are encountered:
GBitmap *fb = graphics_capture_frame_buffer_format(ctx, GBitmapFormat8Bit);
uint8_t *fb_data = gbitmap_get_data(fb);
uint8_t *anim_data = gbitmap_get_data(s_bitmap);
for (int i=0; i < 144*168; i++) {
if (fb_data[i] == 255) {
fb_data[i] = anim_data[i];
}
}
This can be optimized too.
EDIT: I've offered a bounty, since I doubt I'll be getting any answers otherwise.
Lately I've been working with listviews and I've decided to add an icon for each item indicating whether it's input or output. The icons add fine, but they're not transparent:
As can be seen, the icons are clearly not transparent. I'm currently doing something like this load the icons:
hImageList = ImageList_Create(16, 16, ILC_MASK | ILC_COLOR32, 2, 2);
if (hImageList != NULL)
{
iIN = ImageList_AddIcon(hImageList, LoadIcon(hInstance, MAKEINTRESOURCE(101)));
iOUT = ImageList_AddIcon(hImageList, LoadIcon(hInstance, MAKEINTRESOURCE(102)));
}
I've tried messing with the flags for ImageList_Create & LoadIcon/LoadImage but have had no luck and to be honest I've run out of ideas.
Any help would be very appreciated.
First up, ImageList_ReplaceIcon copies the icon data when adding it to an image list. So the HICON needs to be released afterwards.
Next, imagelists are natively bitmaps, not icons. And the way you are creating your imagelist makes the conversion of icon to bitmap very ambiguous. ILC_COLOR32 implies the imagelist should be created as a 32bit dib section, which typically contain transparency information via an embedded alpha channel. ILC_MASK instead implies that the internal bitmaps are DDB bitmaps, with the transparency information stored as a 1bpp mask bitmap.
The quickest solution to your problem - take your two icons:
Merge them into a single bitmap resource thats 32 pels wide by 16 high. Fill the background with a mask color :- purple or something.
Create the bitmap using ILC_COLOR|ILC_MASK
Load the bitmap being sure NOT to use LR_TRANSPARENT.
Add the bitmap using ImageList_AddMasked passing in a COLORREF that represents the mask color.
OR, for a better visual effect...
export your PNG data as a 32x16 32bpp bitmap file containing pre-multiplied alpha channel data.
Create the imagelist using the ILC_COLOR32 value.
LoadImage() with LR_CREATEDIBSECTION to load the bitmap as a 32bpp dib section.
Add the image using ImageList_Add()
(the last option is kind of tricky as the number of tools that support writing out 32bit bmp files with properly pre multiplied alpha channels is rather low).
Edited to add the following code sample. Using a 4bpp bitmap created in the dev environment this works just great :-
HWND hwndCtl = CreateWindowEx(0,WC_LISTVIEW,TEXT("ListView1"),WS_CHILD|WS_VISIBLE|WS_HSCROLL|WS_VSCROLL,0,0,cx,cy,hWnd,(HMENU)101,hModule,NULL);
HBITMAP hbm = (HBITMAP)LoadImage(hModule,MAKEINTRESOURCE(IDB_BITMAP1),IMAGE_BITMAP,0,0,0);
COLORREF crMask=RGB(255,0,255);
HIMAGELIST himl = ImageList_Create(16,16,ILC_COLOR|ILC_MASK,2,0);
ImageList_AddMasked(himl,hbm,crMask);
ListView_SetImageList(hwndCtl,himl,LVSIL_NORMAL);
You want to make your icons have a background color that isn't used anywhere else in the icon, like a really ugly purple, and then use LoadImage(..., LR_LOADTRANSPARENT); The flag says look at the first pixel at 0,0 and make everything that color transparent.
Your code looks fine to me, I always use LoadImage instead of LoadIcon but I suspect that doesn't matter. Have you checked that the icons do indeed have transparent areas and don't themselves have a solid background?
My LoadImage calls look like:
HICON hIcon = (HICON)LoadImage(hinstResources,MAKEINTRESOURCE(IDI_ICON),IMAGE_ICON,16,16,LR_DEFAULTCOLOR);
Here... Create an ImageList, as suggested, make your icons into a Bitmap, 16 pixels high, by 16*n long, where n= the number of icons...
Set the background color to 255, 0, 255, like you have done.
Then, load it, and add it to the image list as I did here:
m_ImageList.Create(16, 16, ILC_COLOR16 | ILC_MASK, 7, 1);
CBitmap bm;
bm.LoadBitmap(IDB_SUPERTREEICONS);
m_ImageList.Add(&bm, RGB(255, 0, 255));
GetTreeCtrl().SetImageList(&m_ImageList, TVSIL_NORMAL);
Of course, this was written in MFC, but as you know, it's just a wrapper to Win32...
Outside of this, you are going to have to go to a custom draw control, in which you draw the icon over whatever background the icon happens to be sitting on. There isn't really any magic "transparent" color, that I know of, in any of these controls.
In the case of a custom draw, you need to use code like the following:
#define TRANSPARENT_COLOR (255,0,255)
UINT iBitmap = IDB_ICON_UP
CDC *dc = GetDC();
int x = 0, y = 0;
CDC *pDisplayMemDC = new CDC;
CDC *pMaskDC = new CDC;
CDC *pMemDC = new CDC;
CBitmap *pBitmap = new CBitmap;
CBitmap *pMaskBitmap = new CBitmap;
CBitmap *pMemBitmap = new CBitmap;
int cxLogo, cyLogo;
BITMAP bm;
pBitmap->LoadBitmap(iBitmap);
pDisplayMemDC->CreateCompatibleDC(dc);
CBitmap *pOldBitmap = (CBitmap *)pDisplayMemDC->SelectObject(pBitmap);
pBitmap->GetObject(sizeof(bm), &bm);
cxLogo = bm.bmWidth;
cyLogo = bm.bmHeight;
pMaskBitmap->CreateBitmap(cxLogo, cyLogo, 1, 1, NULL);
pMaskDC->CreateCompatibleDC(dc);
CBitmap *pOldMask = (CBitmap *)pMaskDC->SelectObject(pMaskBitmap);
COLORREF oldBkColor = pDisplayMemDC->SetBkColor(TRANSPARENT_COLOR);
pMaskDC->BitBlt(0, 0, cxLogo, cyLogo, pDisplayMemDC, 0, 0, SRCCOPY);
pMemBitmap->CreateCompatibleBitmap(dc, cxLogo, cyLogo);
pMemDC->CreateCompatibleDC(dc);
CBitmap *pOldMem = (CBitmap *)pMemDC->SelectObject(pMemBitmap);
pMemDC->BitBlt(0, 0, cxLogo, cyLogo, dc, x, y, SRCCOPY);
pMemDC->BitBlt(0, 0, cxLogo, cyLogo, pDisplayMemDC, 0, 0, SRCINVERT);
pMemDC->BitBlt(0, 0, cxLogo, cyLogo, pMaskDC, 0, 0, SRCAND);
pMemDC->BitBlt(0, 0, cxLogo, cyLogo, pDisplayMemDC, 0, 0, SRCINVERT);
dc->BitBlt(x, y, cxLogo, cyLogo, pMemDC, 0, 0, SRCCOPY);
delete pMemDC->SelectObject(pOldMem);
delete pMemDC;
delete pMaskDC->SelectObject(pOldMask);
delete pMaskDC;
delete pDisplayMemDC->SelectObject(pOldBitmap);
delete pDisplayMemDC;
This code decides where to draw the icon, and takes a snapshot of the background, creates a mask for the icon, and then draws it over the background, giving it a fully transparent background...
Hope that helps somewhat. If not, please explain in more detail what you are trying to make happen, and what you are seeing, or what you are NOT seeing...
I struggled with the same issue using an ImageList in a Tree View. I eventually got Chris Becke's second solution to work, creating an ImageList using the ILC_COLOR32 flag and using LoadImage() with the LR_CREATEDIBSECTION flag. This solution, and probably also the first solution, requires what is described below.
Transparency (and themes) are only supported with comctl32.dll version 6+, to use the correct version, the pre-processor directive on this page worked for me:
https://learn.microsoft.com/en-us/windows/win32/controls/cookbook-overview